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13417 Coastal Zone COASTAL ZONE Information INFORMATION CENTER Center W.P. Alaska. Dept. of Natural Resources. GF 85 .F56 1977 State of Alaska Department of,Natural Resources Division of Geological an d Geophysical Surveys COASTAL. ZONE INFORMATION CENTER AREAS OF PARTICULAR CONCERN FOR GEOLOGIC LIN REASONS IN THE ALASKAN COASTAL ZONE BY S. Finley, J. Riehle, K. Emmel October 1977 THIS REPORT HAS BEEN READ BYTHE STATE GEOLOGIST. IT IS A-PRELIMINARY REPORT AND HAS NOT RECEIVED OFFICIAL SURVEYS PUBLICATIONS STATUS, AND SHOULD NOT BE QUOTED AS SUCH, THE AUTHOR(S) ASSUMES FULL RESPONSIBIL.ITY FOR THE CONTENTS 'OF THiS.REPORT. US Department of Conmerce NOAA Coastal Services Centcy. Li@rary 2234 South Hobson Avenue L Charleston, SC 29405-2413 3001 Porcupine Drive Anchorage Alaska 99501 CONTENTS Page Introduction . . . . . . . . . . ... . . . . . . . . . . . . . . Seismic activity and earthquake zones . . . . ... . . . . . . . . . . . . . 3 Waves and related subaqueous . . . . . . . . . . . . . . . . . . . . . . . . 8 Vulcanism . . . . . . . . ... . . . . . . . . . . . . . .. . . . . ... . . . .9 Glacier dammed lakes and outburst floods . . . . . . . . . . . . . . . . . . Distribution of mineral and energy resources . . . . . . . . . . . . Candidate sites for tidewater ports, Brooks Range Mineral Belt . . . . 14 Areas of particular concern Lituya Bay . ... ... . . . . . . . . . . . . . . . . . . . . . . . . . 15 Yaku.tat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Yakutat Bay-Russell Fiord . . . . . . . . . . . . . . . . . . ... . . . 19 Icy Bay . . . . . ... . . . . . . . . ... . . . . . . . . . . . 20 Copper River Delta . . . . . . . . . . . . . . . . . . . . . 23 Va.ldez . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 25 .Columbia Glacier . . . . . . . . . . . . . . . . . . . . ... . . . . . 27 Whittier . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 29 Seward and Resurrection Bay . . . . . . . . . . . . . . . . . . . . . . 31 Lower Cook In'let . . . . . . . . . . . . . . . . . . . . . . . . . . . 33- Anchorage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Knik River Outwash Plain . . . . . . . . . . . . . . . . . . . . . . . 39 Drift River Delta . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 .Kodiak . . . . . . . . . * ' ' ' * * ' * * ' * * . . . * * ' * ' * 43 Scotch Cap, west end of Unimak Island . . . . .. . . . . . . . . . .. . . 45 Shemya Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Pribilof Islands . . . . . . . . . . . . . . . . . . . ... . . . . . . 49 Cape Krusenstern to Cape Thompson . . . . . . . . . . . . . . 51 Wainwright and Barrow and vicinity . . . . . . . . . . . . . . . . . . 53 Prudhoe Bay and vicinity . . . . . . . . . . . . . . . . . . . . . . . 56 ILLUSTRATIONS Plates I Index map showing areas of particular concern . . . . . . . . . . Envelope 2. Distribution of mineral and energy resources -in the coastal zone of Alaska . . . . . . . . . . . . . . . . . . . . Envelope 3 Slope-Stability map of ANchorage and vicinity, Alaska . . . . . . . Envelope Figure A' Major earthquakes in Alaska (1899-1974) . . . . . . . . . . . . . . 4 B Projected maximum intensity contours, Alaska, 1786-1974, with actual reported intensities superposed . . . . . . 5 C General tectonic map of southcentral Alaska . . . . . . . . . . . . 7 D Volcanos of the Cook Inlet area, Alaska ... . . . . . . . . . . . . 12 I Map of Lituya Bay showing runup levels from giant wave of 1958 . . . . . . . i . . . . . . . . . . . . . . ... . . . 16 2 Yakutat, Yakutat Bay Russell Fiord . .. . . . . . . . . . . . . . . 18 3 Icy Bay . . . . . . . . . . . .. . . .. . . . 1 22 4 Copper River Delta . . . . . . . . .. . . . . . . . . . . . 24 5 Valdez . . .. . ... . . . . . . 26 6 Regional setting of Columbia Glacier . . .. . . . . . . . . . . . . 28 7 Whittier . . . . . . . . . . . . . . . . 30 8 Seward and Resurrection Bay. . . ... . . . . . . . . . . . . . . 32 Page Figure 9 Lower Cook Inlet-Kachemak Bay . . . . . . . . . . . . . . 35 10 Map of area of ashfall from eruption.of Mt. Spurr, 1953 . . . .. . . 38. 11 Knik River Flood Plain . .... . . . . . . . . . . . . . . . . . . . . 40 12 Drift River Delta . . . . . . . . . . . . . . .. . . . . . . . . . . 42 13 Kodiak and vicinity . . . . . . . . . . . ... . . . . . . . . . . . 44 14 Scotch Cap-Unimak Island ..... . . . . . . . . . . . . . . ... . . .. 46 15 Shemya Island 48 16 Pribilof Islands* . . . . . . . . . . . . . . . . . . . . . . . . . 50 .17 Cape Krusenstern . . . . . . . . . . . . . . . . . . . . . . . . . . 52 18 Wainwright.and vicinity . . . . . . . . . . . . . . . . . .. . . . . 54 19 Barrow and vicinity . . . . . . . . . . . . . . . . . . . . . .. . . 55 20 Prudhoe Bay and vicinity . . ... . . . . . . . . . . . . . . . . . . 58 Table I Area of particular concern grouped by geological hazards . . . . .@. 2. 2 Modified Mercalli Intensity Scale of 1931 . . . . . . . . . . . . . 6 3 Summary of recent and active volcanos, southcentral region . . . . . 10 ERRATA SHEET Page ii: Line 3, add after "subaqueous'' the word "sliding" Line 35, should read "Slope-stability map of Anchorage.and vicinity, Alaska'' Pagination for.plates should be ''attached" not "envelopeii Page 3: Line 30, "XIII" should be "XI W Page 19: Line 12, ''Russel" should be ''Russell'' Page 20: Should be page 21 and page 21 should be page 20. Once the numbers are corrected, the sequence should then be reversed Page 25: Line 27, "ficilities" should be "facilities" Page 33: Line 20, "particualr" should be ''particular'' Line 41, "65 miles" should be "105 km" Page 43: -Line 34, add after "materials" the words particularly as armor riprap" INTRODUCTION The following report identifies areas of particular concern (APC's) for geologic reasons in the coastal zone of Alaska. This report was prepared by personnel of the Division of Geological and Geophysical Surveys for the Coastal Management Off ice of the state of Alaska, under a reimbursable services agreement. This project was supported in part by,federal Coastal Zone Management Development funds.(P.L. 92-583, sec. 305) granted to the State of Alaska by the Office of Coastal Zone.Management, National Oceanic and Atmospheric Administration, U.S. Department of Commerce. -For the purposes of this report, APC's have been interpreted mainly as being those areas,along the coastline in which a geologic process presents a significant hazard to life or to property. In particular, this report identif-ies ohly.areas of particular concern at the statewide level. Many areas which have potentially hazardous geologic conditions were not included here because, in the judgment.of the compilers, the potential hazards were of more local or regional concern than of statewide concern. A haza rd is a possible source of peri.1 or danger Geological hazards are those which arise from the materials of the earth, the changes which the earth has undergone or is undergoing. This repo.rt identifies the more significant areas where geological hazards are presently affecting sites in the coastal zone of Alaska. In order to define the specific areas shown herein, no formal definition of ''coastal zone" has been employed. Instead,the initial assumption was to consider only areas of present or likely future development immediately adjacent to the coastline. The entire area of a particular hazard which could affect such developments was then defined to the lim*it of available data. Thus, APC's subject to potential river flooding may extend.inland from the coast for several miles. In addition to geologic hazards, a section has been included on mineral and energy potential in the coastal areas (Plate 2) . The areas selected as being of particular concern are listed in Table 1. grouped roughly by the type of hazard present at each site. They are presented geographically in the report, starting in the southeast, working clockwise around the coast] ine (Plate 1) . .This report is not a complete record of all the hazards along the coast of Alaska. The coastline of A-laska comprises more than 30,000 miles and is.mostly uninhabited. Much of-the coast has never been mapped in detail geologically; even where it has been mappedi such maps were often not for the purposes of identifying geological hazards. Thus, there is a paucity of data on the geological processes in the coastal zone. One of the gu iding criteria used herein to identify areas of particular concern is the proximity of a geological hazard to human habitation or zones of probable development. A natural geological process only becomes a hazard when it endangers man or his developments. Thus, if there is nobody to be endangered, there is no hazard. However, this does not imply that an area not mentioned in this report is-hazard-free*. The areas of particular concern have been defined by two main criteria. Fi 'rst, the geologic hazards identified herein are based on-available data; where no data exist, no hazards can be identified. Second, after identifying the potentially*hazardous, areas, only those areas were defined as APC's which have present development or likely near-future development and which could be adversely affected by the hazards. A further limitation arises from the fact that only geological hazards of regional consequence were considered. For example, many sections of coastline are susceptible .to problems'like ground subsidence, avalanching and slumping. However, such occurrences are usually of strictly local significance.and are so numerous that to catalog them would be a task beyond the scope of this report. Some hazards, such as those arising from presence wi thin seismical ly active proas, are incapable of accuraLe del incaLion but have been discussed in order to bring attention to.their existance. Other hazards, such,as all 'the areas of severe coastal erosion, have not been sufficiently researched or Table I Areas of particular conce rn grou,e I by geological hazards. Waves and Related Subaqueous Sliding Lit'uya Bay Yakutat 'Valdez Whittier Seward and Resurrection Bay Lower Cook Inlet Eastern Coastlino Kodiak Scotch Cap - West end of Unimak Island Shemya Islands VoIcanism Anchorage Drift River Delta Pribilof Islands Glacier Dammed Lakes and Outburst Floods Yakutat Bay - Russell Fiord Copper River Delta Knik River Outwash Plain 'Drift River Delta Coastal Erosion and Deposition Icy Bay Cape Krusenstern to Cape Thompson Wainwright and Barrow and Vicinity, Prudhoe Bay and Vicinity I.ceberg Dr H t Icy lay Columbia Glacier .Other Anchorage (Slope Stability) Pribilof Islands (Seismicity) 2- identified in the literature, and-cannot be included at this time. Note: Each section contains a.paragraph on general geologic setting. The geology was usually taken from the source listed as a reference. Howeve,r, the following two maps were also consulted and are useful for defin.ing the general geology of Alaska: . Karl storm, T,.N.V. , (COITIpi ler) and others*, 1964, Surf i cia:11 Geology of Alaska, U.S. Geol. Survey Map 1-357; Beikman, H.'K., (complier), 1974, Prelininary geologic map.,of the southeast quadrant of Alaska, U.S. Geol. Survey MF-612. Seismic Activity and.Earthquake Zones Although data on Alaskan earthquakes are avail,able back to the late 1700's, the earthquake record for the state is generally incomplete. In the past 75 years scientific interest has grown in Alaska as a whole, and one of the principal results has b.een.increasingly accurate seismic records.@ For example, accurate and complete records of earthquakes less than magnitude 6.0 are available only since about 1963. The earthquake activity has been concentrated along the A leutian Islands, coincident with the chain of active volcanos located there, and along the Gulf of Alaska coast. However, the entire Pacific coast of Alaska and the Aleutian Archipelago lie along* a particularly active section of the Circum-Pacific seismic belt, which is geologically related to the "Ring of Fire" discussed in the section on vulcanism. In the past 75 years, nine shocks have exceeded magnitude of 8, the largest near Yakutat in 1899 (8.6), the next largest in the Aleutians in 1957 (8.5) and in Prince William Sound in.1964 (8.4 -. The Great Alaska Earthquake). About 7% of the annual world-wide seismic energy1s released by earthquakes in the Gulf of Alaska - Aleutian region alone..- Figure A is a small scale map of the major earthquakes in Alaska for the period 1899-1974, given in terms of magnitude. Magnitude is a measure of the size of an earthquake as recorded on a seismogram and is.roughly related to the energy release at its focus. Figure B is a small scale map with the projected maximum intensity con- tours in and near Alaska for the period 1786.-1974 with actual reported intensities superposed. An earthquake intensity, expressed by the Modified Mercalli Intensity Scale of 1931, is a somewhat subjective measure of the effects on people and man-made structures. Intensity, which is expressed in Roman numerals, from I to XIII, is an effecti ve shorthand for describing the maximum effects.of a particular earthquake at a specific local itY (Table 2). Figure C is a generalized tectonic map showing selected structural features of south- central Alaska., Included on this map are faults with known recent or historic movement. It is possible that surface breakage could have occurred along fault's during other' earthquakes in Alaska, but such features easily could have gone undetected if they occurred.in the uninhabited areas. Any.site should be investigated in detai'l for faults before development, especially where large, costly structures or structures for permanent human occupation are anticipated. Areas near to the known act,ive faults shown on Fig. C ,should be treated with:particular concern in this respect; .structures should not be located across the trace of faults, and design should a] low for the effects of lateral and Vertical accelerations 6f*structu.res in'the event of earthqUakes.on the faults. Near.-fault horizontal ground motions have been chara cterized for design earthquakes along the Trans-Alaska Pipeline corridor. Subject to simplifying assumptions and to the uncertaintainties of limited data,' the values of maximum horizontal acceleration are 1.2 a -3- ------- --- ;r co I'D Lo (D \47, ZJ cn_ ai <\ '7) x Ix Al N, -@ska Earthquake -----6@icenter----Qf G' r a t Aq X-1 27, 1 96A - A,\ A N, NN Z- 54 A VU Ix N, Ll- 5 C, T 'IN 50 f 48 %\ L IN, % igure B' ProjeCLed r@ ten@ I ty con tc5u rs ctua I \repo'r @ed -',!'n tens i t i es.---- @Alas@a 974'@,---WiTV@@Mllm 46 786 i,ed Hercall i Sca-4-e-See Table 2@- From superpos d- r@C @ra/t 44 0 4- --o- e NNNN 'A ntehsi y d others\ (1976) ers rea,s of PIC rcc3 --X gr 6ter. )d i 42 I A A IAn IA@ 12 A 121 Icr ICA len ICA AD IAP I'D on 70 17A Ira Irp It" Irn IrA c W (ABRIDGED) Sigined structures; some chimneys I. Not felt except by a very few under broken. Noticed by persons driving specially fnvorable circumstances. (I motorcars. (VIII Rossi-Forel Scale.) Rossi-Forel scale.) VIII. Damage slight in specially designed II. Felt only by a few persons at rest, espe- stuctures; considerably in ordinary cially oil upper floors of buildings. substantial buildings with partial col- Delicately suspended objects may lapse; great in poorly built structures. swing. (I to II Rossi-Forel scale.) Panel walls thrown out of frame III. Felt quite noticeably indoors, especially structures. Fall of Chimneys, factory on upper floors of buildings, but many stacks, columns, monuments, walls. people do not reconize it as an earth- Heavy furniture overturned. Sand quake. Standing, motorcars may rock and mud ejected in small amounts. slightly. Vibration like passing of Changes in well water. Persons driv- truck. Duration estimated. (III ing motorcars disturbed. (VIII+ to Rossi-Forel scale.) IX- Rossi-Forel Scale.) IV. During the day felt indoors by many IX. Damage considerable in specially (de- outdoors by few. At night some signed structures; well-designed frame awakened. Dishes, windows, floors Structures thrown out of plumb; great disturbed; walls make creaking sound. in substantial buildings, with partial Sensation like heavy truck striking collapse. Buildings shifted off founda- building. Standing motorcars rocked tion. Ground cracked conspicuously. noticeably. (IV to V Rossi-Forel underground pipes broken. (IX + scale.) Rossi-Forel scale.) V. Felt by nearly everyone, many awak- X. Some well-built wooden structures de- ened. Some dishes, windows, etc., stroyed, most masonary and frame broken; a few instances of cracked Structures destroyed with foundations; plaster; unstable objects overturned. ground badly cracked. Rails bent. Disturbances of trees, poles, and other Landslides considerable from river- tall objects sometimes noticed. Pen- banks and steep slopes.Shifted sand dulum clocks may stop, (V to V1 and mud, Water splashed (slopped) Rossi-Forel scale.) over banks. (X Rossi-Forel scale.) VI. Felt, by all, many frightened and run X1. Few, if any, (mansonry) structures re- outdoors. Some heavy furniture main standing. Bridges destroyed. moved; a few instances of fallen plas- Broad fissures in ground. Under- ter or damaged chimneys. Damage ground pipelines, completely out of slight. (VI to VII Rossi-Forel scale.) service. Earth slumps and land slips V11. Everybody runs outdoors, Damage neg- in sorf groundd. Rails bent greatly. ligible in buildings of good design and XII. Damage total. Waves seen on ground construction; slight to moderate in surfaces. Lines of sight and level well-built ordinary structures; consid- distorted. Objects thrown upward into erable in poorly built or badly do- air. Table 2: Modified Mercalli Intensity Scale of 1931. -6- 60, 159-* 1512* 148* 144* -J, In z4"@71 Fj ak N A@WT 2r RIVE9 4 LOWL@A& EY Tv. -77-v v-,/ 0,@ -7 A 2 ........... -V 4v 2 e_ CZ1 ............ . ...... .... . 711 ............... F,- 0 Z,@ J Appoxirnatf- COntaCt fault on:-et@. D.Ph,d vh,,e inferred or coric,a;ed. -erse fault Th, ust or re% ........ Da@hed h,,c in ... ...... .(erred. Saurwh on upper .......... op- 1-:h indira@r rnw., fault W ....... Z 10 nZ_ zleeply dipping fault e. Dashed .-here inferred. Arrou-F indirate rf:aire on lateral di,p@;acf ment; bar and ba, d- nth r.u eide -C . . . . . . . . . . . . 7 Trend lines showing s r i k eof Le@ding, v schistosity, an(i folds Majo, faults and faults @ith known Holocene mox-cment -n Holocene rno@ernent; double asteisk indicates historic movement !As-wrisk indicates k I) wA No Fault Data Soi-,--ce J, FaiTNN-eather Tocher W160);Tarr and Martin (19112)-PlaNc, (1967) 2. :Chugach-St Elias (probable M iller and others (1 @59. p. 42); PIZ' ker H 67, @Holocene movement) 5,00 31 Denali St. Amand (1557); Hamilton and Myers(1966@Grantz (1966)1 4- .Laqtle Aftn-Lak-e Clark Martin arid Katz N 912. p. 7. 2-7, 5): Kelly (1963. p. 2 @9); . I Grantz (1965. sheet 3) 5. "Bruin Bay Burke (1@66, p. 139); R. L. Dc-erman, (oral commun., 1967) 0 100 200 300 MILES 6-- Patton Bay and l1anning Bay Plaf ker (I 96S) 7*@ RarVed N1 tn M iller (1961) 0 100 200 300 KILOMETERS S* 11olitna-Togiak Hoare (1961, p. 608-610) I i 9. 1Xenai lineament This paper SUBMARINE CONTOURS IN METERS (possible f964 movement) Figure C: General tectonic map.pf southcentral Alaska. From Plafker (1969). 1 .05 times gravity (that is, 1.2 9 and 1.05 g) for magnitude 8.0 and 7.0 earthquakes, respectively. Levels of horizontal acceleration which would be exceeded 10 ttm,es in a single earthquake are .7 g and .55 9 for magnitude 8.0 and 7.0 events, respectively. The dur'ation of shaking (time between first and last accelerations equal to or greater, .than .05 9) may strongly influence the extent of damage; values for 8.0 and 7.0 events are 60 seconds and 25 seconds. Peak horizontal acceleration values and duration values decrease with distance fro m the fault source of the earthquake, beyond some minimum distance which is greater for larger earthquakes .(Page and others, 1972) - There are a multitude of problems and geologic hazards which accompany the de velopment, of land within a seismically active area. Some of these problems have been.the basis for APC's identified in other parts of this report, such as tsunami's and submarine sliding Due to scale limitations, others-cannot be covered in this report. For. example, hazards which are judged to be of local significance have not been included, even though such hazards can bear significantly on the cost and stability of. local man-made works. Such hazards include surface cracking and fracture, local landsl iding, surf icial subsidence from compaction of unconsolidated sediments ' liquifaction of saturated sediments, avalanching and direct vibratory shaking resulting in structural damage. These hazards are largely cont.rolled,by local geology and features. The maps of seismicity and faulting included wi't.h this report are of necessity too large to show specific zones of earthquake occurrence. The nature of the hazard is such that the local geology must be investigated in detail to determ.i.ne the extent of the risk at,the specific site in interest. Note that because the southern coast of Alaska is in such a seismically active area, no coastal site in these-regions can be considered.free of possible damage from a potential earthquake. Waves and Related Subaqueous Slides Most major earthquakes that involve vertical tectonic displacements beneath the sea are followed by seismic sea waves, which are also referred to as regional tsunamis. The earthquake of March 27, 1964, The Great Alaska (Prince William Sound) Earthquake, generated one of the largest seismic sea-wave trains of modern times.' Waves generated ,by volcanic activity, such as by Mt. Augustine in 1883, are termed local tsunamis ,Sudden violent local waves were the major cause of property damage and casualties in the 1964 earthquake. This sort of wave originates near shore as a result of subaqueous sliding, seiches, subaerial landsliding, tectonic movements or a combination of those phenomena. These local waves affect areas of limited extend and should be distinguished from regional tsunamis. Considerable damage to nearshore facilities can be attributed to the subaqueous sliding which in turn generates destructive local waves. In Alaska, the completeness of the record of tsunamis and the reliability of such information has depended largely.upon cultural development along the coasts. The earlier tsunamis are,not well recorded and what little information has been passed down is often fragmental and uncertain. The 1964 earthquake generated a regional tsunami which caused 20 deaths and destruction along the Alaskan coast from Kodiak Island to Kayak Island. Information on that event is voluminous, and the catalog of dan ' iage i mp rc s s i ve. BCCaUSC of thcsc factors, this Lsunami has provided the main basis for analysis of tsunami hazard along the southern coast of Alaska. A problem associated with the problem posed by inadequate records is that the appraisal of risks involved on the occasion of a seismic event depends upon a knowledge of the range of theeffects of a tsunami which may be expected. Uncer7 tainties are great in Alaska since the record is short and incomplete and the coastal configuration is complex. These variables taken together with the fact that an earthquake which may generate a -t.slunami could occu,r nearly any place along the southern coast of Alaska and out into the Aleutian Chain make the prediction of tsunami risk at any particular place unceryin. It must be emphasized that the areas which have been selected as being of particular concern are those for which data are available and for which a tsunami has resulted in considerable damage, or death. Many uninhabited areas along the coastline are susceptible to -tsunami hazards and many of the other populated areas in Alaska, part- icularly in the Aleutian Chain,have records of tsunamis which have' not-ca used significant damage. For the purposes of this report, a runup height of 2-3 meters has been. selected as.the dividing line for inclusion of areas, since an analysis of the data indicates that runup heights below this level have not normally resulted in significant damage.. Runup,heights have been taken from the avai,lable literature, and although no uniformity is used,,most refer to the height above the existing tide levels at the time of the occurrence. It inust be recognized that damages from tsunamis in the identified areas of particular -concern and elsewhere could have been more extensive if the tsunanli had.struck at high tide levels. While the areas of part.icular concern discussed in.this report are inclusive of the available data, they are not intended necessary to be predictive of areas which will suffer similar damage in the event of another major earthquake such as that in 1964. The areas were selected solely because loss of life or significant property damage occurred at these places in the past, or because recent development activity is occurring and it is possible that similar damage could occur again. The same problems involved in recording regional tsunamis of earthquakes origin are present in dealing with local waves generated by subaqueous slides and other means. Past records are incomplete, and.some waves occur far from areas of habitation. Additionally, the mechanics of submarine failure are not always well understood or capable of ascertainment. Thus, uncertainties in degree of the effect and place of occurrence are great. The Great Alaskan EaTthquake of 1964 produced large scale subaque ous sliding in several of the key port cities in Alaska, causing extensive damage. The majority of the deaths are directly attributable to this cause. Numerous slides are known to have occurred in the area of Prince William Sound and the adjacent Kenai Peninsula, Areas.selected as being of particular concern and particularly susceptible to damage from local waves are those for which data are available and which have suffered from the'effects of local waves in the past. As with the regional tsunamis, a cutoff point of 2-3 meters of runu.p has been selected for the reason previously discussed. Similarly, the runup heights are those 'from the level of the tide at the time of occurrence and the possibility of greater damage resulting from an occurrence at high.tide level must be considered. The areas of particular concern identified in this report by this critieria are not exhaustive and are not intended to be predictive of areas which may suffer simila'r damages from more localwaves. Vu-Icanis The soutmhcentral region of Alaska is an integral part of the "Ring of Fire" which rims the entire Pacific basin. Including the volcanos which are strung out along the Aleutians, there are at least 60 volcanic c'enters in Alaska which have CrUpLed i 11 the pas t 10, 000 yea rs and wh i ch shou I d be cons i de red poten t i a 1 1 y e rupt i ve. About 20 vol canc ranging from Mt. Martin in the south to Mt. Torbert in the north, are of pos-s.ible concern to communi ties on the coast (Table 3) . There are three areas of particular. concern where recent eruptions have caused significant damage, adversely affected. human activities, or have the potenti,al to do either in the immediate future. The areas all lie in the Cook Inlet region. They are Anchorage (fig. 10), the Drift River flood plain (fig. 12),'and the eastern half of Lower Cook.inlet (fig. 9). -9- Table-3: Summary of recent and active volcanos, southcentral region. Approx. Summit Height Date of Last. Name feet (meters) Eruption Martin 6,050 (1,844) Mageik 7,295 (2,210) 1953 Novarupta 3,200 (825) 1912 .Knife Peak 7,6oo (2,316) Tri dent 6,oio (1,832) 1968 Katmai 6,715 (2,047) 1931 Denison 7,4oo (2,256) Steller' 7,4oo (2,256) Kukak 6,6oo (2,012) Kaguyak 2,956 (855) Fourpeaked 6,903 (2,104) Douglas 7,000 (2,134) Augustine 4,304 (1,312) 1376 Iliamna io,ojiG (3,052) 1953 Redoubt 10,197 (3,108) 1968 Double 7,192 (2,192) Black 6,509 (1,984) Spurr 11,070 (3,374) 1954 Torbert 10)000 (3,230) 1953 From: Alaska Regional Profiles, Southcentral Region; Univ. of Alaska, Arcti c Environmental Information and Data Center, 1974. -10- Hazards associated with a violent volcanic eruption include severe blast effects, nuees ardentes, pyroclastic flows, lava flows, volcanic mudflows, turbulent clouds, of ash and hot gases, lightning discharges, corrosive rains, flash and outburst floods, earthquakes and tsunamis. All of these primary and secondary phenomena have occurred in the southcentral region of Alaska in historic times. Of these effects, the most severe which could affect populated areas is the possibility of tsunamis,'and secondarily, the possibility of ashfall or corrosive rains, and flash or outburst floods. For the purposes of this report, volcanic areas of particular concern were defined, on,the basis of combined areas of historical eruptions and areas of population. The active volcanos are situated along the western side of Cook Inlet and Shelikof Strait and the areas of population are situated on eastern shores, (fig. D). Aside from the damage caused by a volcanic-generated tsunami, most effects Of vulcanismon the populated areas would be short term. These effects include inter- ference with air traffic, roof collapse, destruction of foliage or agricultural crops and corrosion of exposed metal. Though no.t necessarily damaging, the removal of ash could require considerable expenditure of labor and money. Areas on the west shore of Cook Inlet which lie.near the flanks or within the drainage area of an active volcano,. such ascrithe DrijftRiver flood plain (fig. 12), should ant.icipate the. possibility of destructive floods and mudflows. Volcanos are b y their nature u npredic.table. Research is ongoing t o enable scientists to predict with greater accuracy exactly when to expect a volcano to erupt. The. effects of eruption are similarly difficult to predict, since each eruption may manifest different symptoms or effects. For example, ash fall and corrosive rains are dependent upon,wind velocity, wind direction, particle size and density, and how high into the atmosphere the particles may ascend. Thus, areas affected once, such as Anchorage, may no.t have similar damage in a subsequent eruption. Glacier Dammed Lakes and Outburst Floods Glaciers cover an area of about 28,500 square miles in Alaska. They.occur principally .along the Pacific coast, in the southern central part of the state. Some.of these glaciers flow across mouths of adjoining valleys and thereby cause lakes to form behind them. When these ice.dams fa-il, catastrophic flooding may occur. A second kind of flooding may occur when a glacier clad volcano begins to heat up and become active. In that case, very rapid melting of the glacial ice can result in the dis- charge of large amounts of water. Both kinds of flooding have occurred in Alaska, and could potentially reoccur at any time. Flooding Imay occur in either.case at any time of the year and is extremely difficult to predict. Many of the coastal areas inwhich flooding occurs are either unpopulated or are identified as s"ubject to flooding by other means. However, floods resulting from glacier dammed lakes present a serious potent ial hazard to population in several parts of the state and a very real limitation to development in areas of potential inundati,on. The areas identified in this report as being of particular concern are those where noteworthy outbursC floods have occurred i .n Lhc past and which are locaLcd in and near arcas of development or potential development. Distribution of Mineral and Energy Resources Plate 2 is an attempt todel inenate those coastal areas of Alaska with the highest potential for nonrenewable resource deposits. The assumption in presenting Plate 2 is that such areas are also those most likely to have exploration and development activities in the foreseeable future. Hayes Volcano Mt. Spurr Volcano A.nchorag . Ken ai Redoubt A Volcano Kasilof Cohoe Iliamna A, Volcano Ninilchik Happy Valley Anchor Point Homer Seldovic Augustine Volcano English Bay Port Graham C-3 Mt. Douglas Volcano 0 50 100 Krn Fj.giire D Volcanoes of tl-ie Cook InIct. area, Alaska. Specific areas have not been defined as APC's for reason.of containing unusual deposits of nonrenewable-resources. Instead, Plate 2 shows those coastal areas which are judged to have the highest potential relative to the entire remainder of the* ,state for the occurrence of a variety of nonrenewable resources. Whether any par- ticular one of these area's will ever be exploited depends not only on economic feasibility, but also on decisions of a political nature which go to issues of competing land uses, "highest use'', and so forth. One of the purp oses of identifying APC's is to aid in making wise coastal land management decisions, Consequently, i.t would be counterproductive (and technically impossible) to identify as APC's,only those specific areas which'are now su-pporting or will support in the very near future nonrenewable resource exploitation. Hence, areas of high potential for minerals and energy are shown at a relatively small scale. Data on coal, oil and,gas and minerals are shown on Plate 2. These data are subject to important constraints on interpretation. First, on-shore (3 - mile) areas with relatively high energy and'minerals potential are based on priority rankings of 500,000 acre tracts for the entire state... The,areas are defined in* part by the boundar 'ies of geologic (rock) provinces. Second, the minerals and coal. rankings are relative to all land in the Stale; the oil-gas rankings are only for those land areas known.to be underlain-by potent.1al reservoir rocks (mainly sedimentary rocks). Third, the rankings for each of the three classes of resources were made independantly of one another, and in general representthe relative like] ihood of exploitable resources being found. "Exploitable" includes consideration of the unit value of the.particular resources, potential size and concentration of the resource, and likely future demand (criticality) for the resource. Fourth, and most important, the rankings are based on the total data available to Department of Natural Resources personnel at the time of compilation. Many areas of Alaska have been explored in detail but the data are proprietary and not available to the public; other areas have been explored only in reconnaissance fashion. In such cases of limited data the relative rankings represent the best professional judgment of.the compilers, based in part onextrapolation of geologic conditions from adjacent areas. In compiling Plate 2 from the original maps of individual resource classes, it was decided to show only the areas for each resource class which fell in about the upper one-third rank of all areas for that class. While such a decision is basically arbitrary, it seemed necessary in view of the requirement to define only areas of particular concern.. On the other hand, to restrict the areas shown to only the upper 10% or so seemed to be potentially misleading; several of the highest rankings have been explored and announced only with the past few years and it is likely that future discoVeries could be made in lower ranking tracts which are relatively unknown at present. In view of the.aforementioned limitations, the areas shown on Plate 2 should be con- sidered-onlyas a general guide to coastal areas most likely to contain exploitable nonrenewable resources. Available data on specific deposits (for example, U.S. Borax molybdenum deposit in southeastern) have been incorporated in ranking,the broader areas shown. While such deposits are.obviously areas of particular concern at present, future exploration and exploitation will occur in other areas as well. Despite a growing public awareness that our nonrenewable resources are limited and that rational alternatives to exploitation must be developed, it is in the national interest that reasoned exploitation continue for the foreseeable ' future. Nonrenewable resources are an important part of Alaska's total resource base, and reascried exploitation can be in the. best interest of the State. An awareness of known regDurce deposits,. and of the areas most likely to contain as yet undiscovered -13- deposits, i snecessary to complete a coastal management scheme. Areas can be tentatively identified for management purposes as possible areas of resource exploitation, a'nd some areas of potential use conflict may be recognized early. Plate 2 also includes the areas which might be capable of development.as geothermal energy sites. Candidate Sit es for Tidewater Po rts, Brooks Range Mineral Belt The general area of the.Brooks Range and Seward Peninsula has relatively high mineral potential. In'the event that large-sc,ale production is undertaken there, it is likely that overland shipment of ores would be to a tidewater port on the Seward Peninsula. Due to hazards posed by storm waves, shallow water, potentially unstable bottom, and annual ice, candidate sites for such-a port or ports are probably limited to a few areas. Several members of the mineral industry in Alaska have expressed their opinions on.the ost likely candidate sites. Because there is agreement among such members, we tentatively identify as APC's the following sites. of potential tidewater ports (sites m are shown on Plate 1). We have no detailed data on onshore and near offshore geologic conditions, nor do we know the precise likely locations of potential facilities within the general area of each site. Thus, the sites are identified only tentatively and are shown only at smal I scale on Plate I. (a) Cape Darby (b) Point Jackson (c) Cape Nome (d) adjacent to the south end of the Mulgrave Hills, about two-thirds of the distance from Cape Krusenstern toward Kivalina. (Sites.are ranked in order of,relative preference expressed.) -14- Lituya Bay A. Geographical Location 1. Region: Southeastern Alaska, Easteen'Gulf'of Alaska 2. Latitude: 580 361 4511 N Longitude: 137' 391 3011 W 3. Additional Information- U.S. Geol. Survey Quad. Mt. Fairweather (C-5, C-6), scale 1:63,360. B. Area Description 1. General geologic settin g: Lituya Bay is a long narrow inletopening south- west onto the Gulf of Alaska. The deposits at the mouth of the bay consist of slightly modified.glacial moraines and associated drift. These Quatexnary deposits overlie late Tertiary -siltstone, sand-stone and sandy mudstone with locally abundant volcanic rocks, which are.exposed on either side of the bay. The head of the bay is composed,of Jurassic to Cretaceous graywacke, slate and minor conglomerate. The Fairweather fault, trending northwest, cuts across the head of Lituya Bay. It is probable that the bay Js a valley which flooded after the retreat of Lituya Glacier, and/or North Crillion Glacier. The walls of the northeast end of the bay are remarkable for their steepness. 2. Criteria employed in identification as an APC: Lituya Bay is known for the giant waves produced by rock masses s.liding from the steep walls at the head of the bay into the areas of the bay itself. In 1853 or 1854 a landslide produced waves with a runup in excess of 115 meters.Other land- slide generated waves occurred in 1874 ( 6 m..), 1899 ( 60 m. -possibly triggered by earthquake near Yakutat), 1936 ( 140 m-destroyed two cabins on Cenotaph [sand) and on July 9, 1958. The 1958 slide was triggered by a magnitude 7.9 earthquake and subsequent movement along the Fairweather fault system. The 1958 wave stripped off the forest on the opposite side of the fiord to over 5Wmat -ers,wrecked two boats, caused two deaths and produced a wave over 9.0,"meters high at the mouth of the bay. About 35 million cubic meters of material from as high as 900 meters altitude slid from the northeast wall of Gilbert Inlet. 3. Reasonfor inclusion of this area as an APC: Although there are no per- manent settlements in Lituyc-3 Bay, the event of July 9, 1958 indicates that. Ithe unique conditions which exist at Lituya Bay are a potential threat to life and.property. Boats have.been anchored in the bay when slides have occurred. Moreover, knowledge gained by study of the phenomenon which occurs.with regularity in Lituya Bay may aid in preventing or anticipating similar occurrances.in other areas near population centers. 4. Other: See figure 1. Reference:. Miller, D.J., 1960, Giant waves in Lituya Bay, Alaska, U.S. Geol. Survey Prof. Paper 354-C, p. 51-86. -15- 137' 347 3000 N @000 \325 -1000 @0011 r,0 0 2000 17,?3 WCY 175\ ..... \--125 '--220 130 165 160 @Ce 04, 90 -/4- 90 @ @_1111131_ -6 95 35@ 65 4 680 CENOTAP ISLANO Cr\ so -5 400 CA;. 1/5 opoo 35 f 30 40 : -1; EXPLANATION 0.... .......... 0 Trimline (upwr limit of destmc. q A -1 tion of forcst by water). show-. 70 ing appr,axim.W.1tit.de ab,'ve S . ....... *"'. C, , 'e-130 mr.nse. level 15 The . .............. A' dhy P. . .. ....... 85 46. ph.(,V,@ t6, 100 - - - - - - - P-t Windrow: of felled tre@@ 35' NOTE: DOI., and gl@6@r fronts Delta sho.n ppr-i-L.1y as th@y .- i-diawly p-- cedi.g the %Mhq..ke and ..'e. Appro.@imate locations of fishing boats at onset of wave 0 1 2 MILES i CONT@UR @NTERVAL 1000 F@ET A DATUM IS APP?OXIMATE MEAN SEA LEVEL Location of wave-eroded marp @,000@ Figure 1; Map of Lituya Bay showing runup levels from giant wave of 1958. From Miller (1960). Yakutat A. Geog ra ph i ca 1Location 1. Region: Southcentral Alaska, Gulf of Alaska 2. Latitude: 590 331 N Longitude: 1390 44' W 3. Addition'al Information: U.S. Geol. Survey Quad. Yakutat (B-4, B-5, c-4, C-5), scale 1:63,360. B . Area Description T. General geologic setting: Yakutat is situated on the southern shore of .Yakutat Bay, which formed by marine inundation of 6 glacially scoured valley upon the retreat of Hubbard (?) Glacier in the past 500 years. The Malaspina Glacier is across Yakutat Bay directly to the north.. Yakutat itself is si.tuated upon prominent, slightly modified glacial moraines and-associated drift left behind by the glaciers as they receded. Directly south of Yakutat are glaciofluvial deposits principally consisti-ng of slightly to moderately modified outwash deposits'. Coastal deposits found along the Gulf of Alaska coast include beaches, spits, and b.ars as well as older.deposits of interlayered alluvial and marine sediments including local glacial drift. To the northeast, at the head of Yakutat Bay and on both sides of Russell Fiord, are graywacke,, slate and minor conglomerate of Jurassic to Cretaceous age. 2. Criteria employed in i'dentification as an APC: Yakutat has been hit at least once in historic times by earthquake generated. tsunamis. On Sept. 10, 1899, an earthquake of magnitude 8.6 occurred approximately 55 km n6rtheast at the head of Disenchantment Bay generating a wave with over 9 M. @ of runup. There were no reported casualties or damage in.1899. However, waves generated in 1848 by a glacier icefall into Yakutat Bay killed 100 people. Similarly, an ice:fal'] into Disenchantment Bay caused waves.-with 35 m of runup in Yakutat Bay on July Li, 1905. 3. Reason for inclusion of this area as an APC: Although there are no reports, of deaths or damage from tsunamis 'in recent years, Yakutat is situated on low lying unconsolidated. sediments and would be susceptible to considerable damage from an earthquake or rock/icefall generated wave. Yakutat is the only development of size on the Gulf of Alaska coastline between Cordova and.Sitka and with the possibility of offshore oil/gas development could increase in size and importance.. Itis the only sheltered port between Lituya Bay and Icy Bay., 4.. other: See figure 2. Reference: Yehle, L.A., 1975, Preliminary report on the reconnaissance engineering geology of the.Yakutat area, Alaska, with emphasis on evaluation of earthquake and other geologic hazards; U.S. Geol. Survey Open-File Report 75-529, 136 p. 177 39 30" All Do' Possible 00 r* N ble ry@v @ta Laitouc N 6 T UNA A A B@zhm 336 746 Inferred direction of travel, Tsunami of 1899 ? X- JA SeatIBay 2650 4i T 25 _2 ?0 Cove 0, 6 50 00 h 'zo U t0i .2 1@ id 630 Humpback eld Areas subject to -are x1ra 5 4a possible Tsunami damage Is, 4a 7Zi ,a @1 6 u8p A P too tos itzger "/Y 7,C 113. 15 ? T 27 S too Aea U 2 W @pe 60" Ocean pp nin % u'ila, @ - @- I - I/ A 70.e Rad%o YaX, at 590 30'@7 _0 T 28 "S R' 01 el C@ .29 Zone of speculated inundation due to outflow from Russell Fiord WA01 if dammed by Hubbard Glacier P> a T 29S @::J L A rig ure" 2, YAKUTAT, YAKUTAT- -BAY, RUSSELL FIORD 0@ Scale 1:2.50,000 E Yakutat Bay-Russell Fiord A. :Geographical Location 1. Region: 'Southcentral Alaska, Gulf of Alaska 2. Latitude: 60' 001 N Longitude: 139* 271 W 3. Additonal Information: U.S. Geol.. Quad., Yakutat (D-4, D-5), scale 1:63,360 Mt. St. Elias, scale 1:250,,000. B. Area Description 1. General geologic,setting: The Hubbard Glacier is 50 km long and covers an area of 3800 square km. - It has advanced.intermittently since first mapped in 1895 and was advancing as of 1977. If it continues to advance, the glacier will eventually close off the entrace to Russel Fiord, a 45 km long arm of the sea which will then become a fresh water lake. A glacier dammed lake was charted in this valley by Russian explorers in the early 1800's. 2, Criteria employed for identificat.ion as an APC: T@ere is no present flood hazard but there is an extreme danger to boats near the glacier margin and in tidal currents at the mouth of Russell Fiord. When dammed, the lake could drain directly to Disenchantment Bay under or along the margin of Hubbard Glacier. Renewed increased overflow to the South as suggested by underfit streams in the vicinity of the present Situk River is highly probable, under such circumstances. 3. Reason for identification of this area as an APC: Although there is no present danger to any of the developments in Yakutat area, the possibility of the the.lake developing behind Hubbard Glacier and spilling to the south should be considered if Yakutat expands to the southeast onto Yakutat foreland. 4. Other: See figure 2. Reference: Post, A., and Mayo, L..R., 1971, Glac ier dammed lakes and outburst floods in Alaska, U.S. Geol . Survey Map HA-455. Yehle, L.A., 1975, Preliminary report on the reconnaissance engineering geology of the Yakutat area, Alaska, with emphasis on evaluation of earthquake and other geologic hazards; U.S. Geol. Survey Open-File Report 75-529, 136 p. 19- .References: (continued) Lahr, J.C., and Page, R.A., 1977, Earthquake activity and ground shaking in and along the eastern Gulf of Alaska, Alaskan OCS Principal Investigators Reports, Annual Report (1976-1977), BLM/NOAA, 31 P. U.S. Department of the Interior News Release, May 4, 1977. -20- Icy Bay A. Geographical Location 1. Region: Southceintral, Northern Gulf of Alaska 2. Latitude: 590 55' N 3. Additional Information: U.S. Geol. Survey Quad., Icy Bay (D-2, D-3), Bering Glacier (A-2, A-3), scale 1:63,360. B. Area Description 1. General geologic setting: Icy Bay is a north-trending fiord adjacent to the Gulf of Alaska. As recently as 1904 the entire area was overlain by glacial ice. The Guyot Glacier has been as much as 10 km seaward of the 1977 shoreline position. A terminal moraine located at the mouth of Icy Bay marks the limit of this advance. Ice retreat which began before 1910 has continued to the present with about - 40 km of retreat through 1977. After the ice retreat,-Iongshore sediment*transport began building a spit complex on the east shore of Icy Bay where it meets the Gulf of Alaska. The spit has continued to develop and has hooked to the northeast. The Gulf of Alaska shoreline southeast of Riou Spit has steadily eroded northward by waves and longshore currents. The shore at Icy Cape is being sim.1larly affected. Recent research indicates there is a zone of earthquake epicenters which extends northeast from the mouth of Icy Bay and implies that an active fault may run down the center of Icy Bay. 2. Criteria employed for identification as an APC: The Icy Bay area has many potentially hazardous or constraining geologic features, such as the shallow submarine moraine at the bay mouth and the icebergs which are constantly produced at the bay's head. The most significant hazard may be the high rates of shoreline erosion and sedimentation. An analysis of aerial photos indicates that the eastern shore has receded as much as 1.3 km in the past 35 years and over 8.2 km2 of the western shoreline has disappeared, including all of Guyot Bay. In addition, Riou Spit may grow to eventually fill the bay. just east of Moraine Island (Seal Camp Harbor). Guyot Glacier could readvance to its 1904 terminal position which could prevent use of the bay as well as any shoreline developments. However, the timing of such an advance is uncertain at present (L. Mayo, pers. comm. 1977). 3. -Reason for inclusion of this area as an APC: Icy Bay is the sole.shelter from storms between Yakutat and Kayak Island. It is the only sheltered bay near many of the offshore tracts that were ]eased for petroleum pro- duction in the April 1976 northern Gulf of Alaska lease sale., and has been considered as a primary onshore staging site for the support of offshore ex- ploration and development. At least one private corporation has expressed interest in it as a development site. The continuing high level of seismicity and possibility that this activity represents,an offshore continuation of an'inferred-thrust fault is an important constraint on development there. 4. Other:' See figure 3. Reference: Boothroyd, J., Cable, M S., and Levey, R.A., 1976, Coastal morphology a nd sed i men ta L i on, Gu I f of Ala.ska. AlaSkan OCS Principal Investigators Reports, July-September 1976, BLM/NOAA, 84 p. 21- 971 /* 00 > Heavy _'00 drif t ice 6000 L U on, Pt Q d=nOr%f%" lanlingk Possible @O .'OJO glacier surge bins 246 Pt 9 ZF zones sul@ject T 22 V IScatteredl to flooding T 23 S Ba' 1drift ice]- (boundaries R26 approximate MorWW. Zone of . . ...... erosion 60 N e4 Do 126 i 2 5 T 4 S 12 Q Glacial moraine 26, 1904 margin deepest point-55' Longshore d r i f t r 'Figure,. 3 d120' ICY BAY from Boothroyd, Cable:& Levey, (1976) Scale., F250,000 Copper River Delta A. Geographical Location 1. Region: Southcentral'Alaska, Gulf of Alaska 2. Latitude: 60'. 33' N Longitude: 1450 45' W 3. Additional Information: U.S. Geol. Survey Quad., Cordova,(C-2, C-3, B-3, B-4) . Sca I e, I : 63,360. B. Description of. Area 1. General geologic setting: Van Cleve Lake is formed behind part of Miles Glacier. The lake has a maximum area of 16 square km, and drains sub- glacia-Ily, probably every-] to 3 years.. An unnamed lake of approximately 2 square k m is formed behind.McPherson Glacier. It drains subglacially. 2. Criteria employed in identification as an APC: Van Cleve Lake drained catas- trophical ly in 1909 and in 1,912, destroying 500 m. of railroad trestle and drowning a man. Thi.s unnamed lake has drained twice within the last 15 years, washing out as much as,a mile of the Copper River Highway. 3. Reason for inclusion of this area as an APC: With the construction of the Copper River Highway now in progress, fu ture floods could present very serious hazards. All development within the delta area will have to take into account the possibility of such a flood occurring. 4., Other:. See f igure 4- Reference: Post, A., and Mayo, L.R., 1971, Glacier dammed lakes and outburst floods in Alaska, U.S. Geol. Survey Map HA-455. _23- -0 1453 00 1, � . . . . . . . . . . . . . . . . .......... 44iles Lak T1 _u A @ V7/, q1o r2' r 1600-:@d- Y nferred limit of f lood zone ell @41 L I F lag AM CA." f I s I a, 'ZI 1@v 0. 170JIM, Zp,, JJ* V, Ic o P P E R R i V All J, 9 L T -A. Lahr R; . vV.+ jr N 0 Kokinh r -4 ras .,Cp V ZO t Mt F ligure 4 COPPER- RIVER DELTA FICIMI, M r*,j proxiniate Polubdaries. op ael arti '250,000 land Sc.ole .1. Va I dez A. Geographical Location .9 1. Region: Southcentral Alaska, Prince William Sound 2. Latitude: 610 07' N Longitude: 1460 16' W 3. Additional Information: U.S. Geol. Survey Quad.,'Valdez (A-6, A-7), scale 1:63,360. B. Area Description 1. General geologic setting: Valdez is located at the eastern end of Port Valdez, which comprises a narrow steep-walled glaciated fiord in the Chugach Mountains, and represents the northeasternmost extension of Prince William Sound. The engineering geology of the area has been extensively investigated because of the Trans-Alaska Pipeline Project. The.bedrotk consists of slate and graywacke. mostly in thlick beds with minor amounts of argillite, arkosic sandstone and conglomerate. At the eastern end of Port Valdez, outwash and alluvial plains from two rivers and from Valdez Glacier coalesce to form and broad delta. This- delta is composed of a.thick section of poorly consolidated silt, fine and sand and gravel and may be as much as,180 m. thick. Along the shoreline-is a thin strip of tidal flats made up of silty,sand and organic mud. The old town was located on these unconsolidated sediments. The new town sits on the Mineral Creek alluvial fan which is composed of medium dense to very dense cobble gravel in a.matrix of medium to coarse sand. This fan is buttressed by an.outlying bedrock ridge. 2. Criteria employed in identification as an APC: The earthquake of March 27, 1964, triggered a massive submarine slide a.lona the entire face of the de'Ita, involving. approximately 98 million cubic yards of material. This slide destroyed the harbor ficili.ties and nearshore facilities. Waves generated by the slide and subsequent seiches did additional damage to the waterfront and the downtown area.".. These waves are estimated to have been 9 to 12 m. high. Fissures developed throughout the fine grained saturated deposits of the delta and caused structural damage in the downtown.a.rea. Some parts of the delta subsided below pre-earth- quake high tide levels. Another massive submarine slide originating mainly at the site of Shoup Glacier end moraine in western,Port Valdez produced waves with runups.of over 35 meters in that area. 3. Reasons for inclusion of this area as an APC: The importance of Val-dez to the economy of the State of Alaska is well known si'nce it is the northernmost ice- free seaport in Alaska and the southern terminus of the Richardson Highway. It is the shortest and most direct route for tidewater to Fairbanks and interior Alaska. Furthermore, it is the southern end of the Trans-Alaska Pipeline and .principal port for, the export of oil. Even though the town was moved to the.. Mineral Creek fan,after the destruction of a.great part of the town in 19614, knowledge of the geologic conditions which exist in Valdez and caused the damage in 1964 may aid in p.lanning i,n other areas of Alaska with similar circumstances. 4. Other: See figure 5. References: Coulter,.H.W., and Migliaccio, R.R., 1966, Effects of the earthquake of March 27, 1964 at Valdez, Alaska, Geol..Survey Prof. Paper p. CI-C36, Plafker, G., Kachado.orian, R., Eckel, B., and Mayo, L.R., 1969, Effects of thE earthquake of March 27, 1964 on various communities, U.S. Geol. Survey Prof. Paper 542-G, p. GI-G50- -25- 7@ 3b I r New high -N tide level 3 432 Jb eral C@ istands Old 4 Zone of failure in 196 L D E Z 71. p 0 T 64 Figure 5 '60 VALDEZ 31' runup in 1964 jo Migiiacc to from Coulter 63o Plaf ker a others (1969) RM I Scale 1'.63,360 Us UM Site of Alyeska pipeline Facilities -12iO 7, mill a I U r 0 Columbia Glacier A. Geographical Location 1. Region: Southcentral Alaska 2. Latitude: 60' 591 3011 N Longitude: 1470 02' 30" W 3. Additional Information: U.S. Geol. Survey Quad., Seward (D-1), Cordova (D-8), Anchorage (A-I), Valdez (A-8), scale i:63,36o. B. Descript.ion of Area 1. General geologic setting:2 Columbia Glacier is the largest glacier in Prince William Sound at 1,100 km .. While most Alaskan tidal glaciers have made large-scale drastic retreats, Columbia Glacier has been in a state of near equililrium for over 175 years, and is the only tidal glacier remaining on the North.American continent which is still in an extended position. Current Columbia Glacier ends on a shoal interpreted to be a terminal moraine, which extends across Columbia Bay. Radar soundings of ice thickness indicate that the shoals at the terminus do not continue under. the ice for any great distance, and for at least 30 km up the glacier much of the bottom is far below sea level. 2. Criteria for identification as an APC: Although the terminus of.Columbia Glaci,er has been,virtually stable, icebergs drift into shipping lanes in northern Prince William Sound and the approaches to Port Valdez. The stability of this glacier is anomalous with that of other Alaskan tidal glaciers, which have previously undergone large scale retreats Large embayments which form at the terminus. may present a serious hazard to' the glacier's continued stability. A drastic retreat would be associated with increased iceberg discharge, and such could occur within a few years should the glacier retreat from the shoals. 3. Reason for inclusion of this area as an APC: The approaches to Port Valdez are the only shipping Ian es to thesouthern terminal of the Trans-Alaska Pipeline. The large number oficebergs floating into shipping lanes produces a significant hazard to vessels such as large oil tankers. 4. Other: See figure 6., Reference: Post, A., 1975, Preliminary hydrography and historic terminal changes of Columbia Glacier, Alaska; U.S. Geol. Survey Map HA-559. Post, A., 1977, Reported observations of icebergs from Columbia Glacier in Valdez Arm and Columbia Bay, Alaska, during the summer,1976, U.1S. Geol. Survey Open-File Report No. 77.-235, 7 p. -27- 150*00' 149*00' 148'00' 147*00' 146*00' 145*30' @61*30' 6 1'30' 0. X\ Valdez N n -Trans-Alaskan Pipeli e 61 *00'. Tern linal 6 1'00' V,@ J U, N CWhittier, 00 C@ Gravina-Point va STERLING Seward 60*00'1- 60'00' r7At -------- 145*30' 150*00' --------- 146*00' 149*00' 147*00' SCALE 1 1 000 000 10 0 10 20 30 KILOMETRES Glacier outlines Figure 6: Regional setting of Columbia Glacier. From Post (197.6). Whittier A Geographical Location 1. Region: Southcentral-Alaska, Prince William Sound 2. Latitude: 60* 46# 30" N Longitude: 148' 41' 00'' W 3. Additional Information: U.S. Geol. Survey Quad., Seward (D-5), scale 1:63,360. B. Area Description 1. General geologic setting: The bedrock in the Whittier area consists of Cretaceous (?) rocks, predominately slate but containing minor amounts of graywacke. Along the shores the bedrock has been intruded by four quartz diorite or diorite dikes or sills. Unconsolidated deposits consisting of outwash and stream gravels form the delta upon which Whittier rests and the southern part of the delta at the head of Passage Canal. The deposits at the northern part of the delta are overlain by a glacial moraine. 2. Criteria used as identification as an APC: On March 27, 1964, an earthquake of magnitude 8.5 struck southcentral Alaska. Submarine landslides.triggered by this earthquake produced at least two, and probably three waves, which. severely damaged the waterfront in Whittier and killed 13 people. In Whittier itself, maximum runup was 13 m. but other parts of.the Passage Canal showed evidence of a maximum runup of as much as 32 M. 3. Reason for inclusion of this area as an APC: Whittier was built during World Was 11 to provide an all weather terminal for the Alaska Railroad. Its importance to the State can be appreciated when it is noted that due to the destruction of the ports at Seward and Valdez during the 1964 earthquake, the loss of Whittier port facilities left Alaska without.any all-weather port for unloading supplies for movement inland either by rail or highway. Because the submarine slopes in Passage Canal were not significantly decreas.ed by the landsliding during the earthquake, more slides and corresponding destructive waves may be expected in the wake of another earthquake of comparable magnitude. 4. Other: The town of Whittier is owned and operated by t he U.S. Government, though some of the' land has been ]eased to private enterprise. See figure 7. Reference: Kachadoorian R. , 1965, Effects of the earthquake of March 27, 19.64, at Whittier, Alaska, Geol Survey Prof. Paper 542-B, P. 131-1321 _29- ,f=@4 C@ % N A T -R E', S! T 'N A- I-L--- RF %TF 1: M-%!,L \N. W, Y, 660050 - cp C.I. 3 31 p V F@ A co A L @AB. - cl- t C)LI 0 E ap, P@ayr*rd' E- -2 J, Mnunlatn 7@) 0 8' r u'6u iup 'N U I Now -FAA -,u 2 T Areas of submarine 1\ c ive. X S J. v sliding rtn e -J) 36'runup La ko, runup-r j- i,,e r S@ Area s6biec't fo damage, from, 7,. s u b m r n e - s I i e\:g e n e r a t e d Wav s Le!, 2@- ILI; J @ortage Pass Figure 7 WHITTIER,' 4b r G,I,y r I I Data from Kcichadooricin(166@ a 7, 7 4@ r) Seward and Resurrection Bay_ A. Geographical Location I.. Region: Southcentral Alaska 2. Latitude: 60' 061 3011 N Longitude: 149' 26' 30" W 3. Addi.tional,information: U.S. Geol. Survey Quad., Seward (A-7), scale 1:63,360. B. Area Description 1. General geologic setting: The town of Seward sits at the northern end of Resurrection Bay. The main part of the residential and commercial area hugs the western side of the bay and is located on alluvial fan and -fan-delta deposits which consist chiefly of loose sand, gravel and silt which have been deposited at the mouth of Lowell Creek. The town is expanding northwardsonto the alluvial plain of the Resurrection River which feeds into the northern end of Resurrection Bay. Deposits there consist of sand and fine to.medium gravel with minor amounts of silt and cobbles. These unconsolidated fluvial and other glacial deposits overlie bedrock which crops out mostly on the steep slopes along the walls of the bay. The bedrock consists of slightly metamorphosed graywacke and phyllite with a few conglomerate beds and is upper.Cretaceous in age. There are some beach, deltaic and estuarine sediments deposited on intertidal flats at the head of the bay and along margins of some of the fans. The surrounding area is very rugged and is characterized by numerous glaciers. 2.- Criteria employed in identification as an APC: As a result of the earthquake of March 27, 1964, slide-generated waves, seismic sea waves and possibly seiche waves overran the shores in the Seward area. Along the waterfront a strip of land about 1200 m. @ong and 15 to 150 m. wide slid into the bay concomitantly with offshore submarine sliding. Large scale sliding also occurr'ei in the delta deposits at the mouth of the Resurrection River. The sea waves were generated by uplift in the seafloor in the Gulf of Alaska and arrived about 25 minutes after shaking stopped. These waves didconsiderably more damage to the already devas,tated waterfront. They had. a runup as high as 12 m., and went as mucn as 1.5 kni inland at the north end-of Resurrection Bay. 3. Reason for inc-lusion of this.area a s an APC: Seward.was-one of the most heavily damaged towns in Alaska as a result of the earthquake of 1964. Much information gained by study of the conditions which led to the damage has been used in reconstructing the town. However, if a major earthquake strikes in the vicinity in the future, similar lands'lid ingand wave dama.ge can be expected. Since Seward is oneof the few icefree ports in Alaska, its presence is criticial to the economy of Alaska. However, it must be recognized that the risk of damage to harbor and dockside.facilities exists since it is.not feasible to relocate them in sheltered areas or to providebreakwaters.to minimize the risks. 4@. Other: See figure 8. Reference: Lemke, R.W., 1967, Effects of the earthquake of March 27, 1964 at Seward, Alaska, U.S. Geol.. Survey Prof. Paper 542-E, p. EI-E43- 31- 1Q 20 21 22 t,-ibo 1@1, I-zw 'VAS!* n 45 61 25 1 Ilk- 04 Zone of submarit L! e o f maximum 31'runup ;:n:D4 1; lq@ 24'to 31' runup ing submarine slid I cracking I Dock A, 23'runup i 1964 77_ 7 05 .35'runu 1P S 51 Point ? 2 130 runup 2 VA Figure 8 V 7?6 SEWARD Data from Lemke (1967) P I of ker (1969) Scale 1'63,000 Lower Cook Inlet A. Geogra phi ca ILocation 1. Region: Southcentral Alaska, L.6wer Cook, Inlet Area 2. Latitude: 59* 15' N to 600 N Longitude: 151' W to 154' W 3., Additional Information: U.S. Geol. Survey Quad., Iliamna, Seldovia, Kenai, Tyonek, Anchorage, stale 1:250,000. B. Area Description 1. Geographical boundaries: Tsunamis generated by volcanic activity on Mt. Augustine have the potential to strike the Lower Cook Inlet shoreline, either on the east or the west shores. However, aside from a few scattered cabins, the west shore is unpopulated whereas the east shore supports several smal.] fishing villages and the towns of Seldovia and Homer. Data are somewhat incomplete for the east shore since the major tsunami occurred before monitoring devices.were available. Accounts which are c-nnfused in the literature are.based mainly upon eyewitness reports.. Thus, only the areasaround centers of 'population have been considered as APC's. Generally, this'defines the area of concern as the low-lying coastal areas oii either side of Kachemak 5ay and-the western tip of the p@rt of the Kenai Peninsula which contains the Kenai Mountain Range. Towns falling within 1hisarea of particualr concern incl ude Homer, Anchor Po i n,, Seldovia and Port Graham. 2. General geologic setting: The area of concern is best divided into two units for the purposes of describing the geology. The area bordering the northern half of Kachemak Bay is an area of low relief. The subsurface bedrock of mid-Jurassic to Late Cretaceous age is composed of continental shelf deposits of sandstone, siltstone, shale, limestone and claystone with some conglomerates and mudstone. This bedrock is overlain everywhere by Tertiary sandstones, shales and conglomerates which are overlain by Quaternary glacial moraine and drift deposits. Along some river valleys are found generally well sorted floodplain,.t.errace and fan deposits. The Homer area is slightly west of the Border Range fault system which trends northeast at the base of the Kena i Mounta i ns and wh i ch i s covered by recent o I ac i a I depos i t s The area on the south side of Kachemak Bay is characterized-by an irregular coastline. Bedrock consists of minor amounts of Tertiary siltstones, sandstone and conglomerates, which overly mildly to strongly metamorphosed Triassic (?) to Cretaceous rocks. These.latter rocks include a deepwater sedimentary sequence of graywacke, siltstone, slate, sandstone and conglomerate interbedded with volcanic basalts and detritus. The BorderRange fault system continues near the coast in this area. 3. Criteria employed for identification as an APC: Mt. Augustine is an island volcano at the mouth of Cook Inlet about 65 miles west of Seldovia across Lower Cook -Inlet. It is primarily andesite, a composition that characteristically produces relatively violent erupti.ons. It has erupted several times in the past 100 years. On October 6, 1883, a particularly violent eruption produced mudflows. and nuees ardentes which descended the sides of the volcano and entered the shoal waters of the north shore of the island, generating sea waves which traversed lower Cook Inlet. At least three waves reported Lo be T-9 111i2ters high hi L Port Graham across the inlet. It is possible that the wave struck considerately more coastline but 33- the area was sparcely settled at the time and records do not accurately reflect the extent of the destruction. 4. Reason for inclusion of this area as an APC: Mt. Augustine is particularly dan- gerous because of its marine location and proximity to areas of population. The tsunami produced in 1883 struck settlements while the tide was at low ebb, but if one struck at high.tide considerable damage or loss of life could result. The shores and flats of Cook Inlet (e.g., Homer Spit) are at present potentially exposed to similar inundations produced during explosive eruptions. Mt. Augustine is active and has'shown considerable.activity recently in 1963 and 1976-, and although it is not possible to predict at this time when another explosion will occur, such an event is not an unlikely possibility. The volcano is being mon.itored presently by geophys-icists from the University of Alaska. 5. Other: It must be kept in mind that designation of areas in Kachemak Bay as APC's is neither predictive or inclusive' There a.re factors associated with an eruption of Mt. Augustine that might have a controlling influence on the effects of such an eruption and which are impossible to predict. Moreover, the amount of data available is insufficient to allow an accurate determination of exactly where a wave generated by volcanic activity would strike. For example, the western shore of Cook Inlet could be struck by tsunam.is generated by a westward flow of material from the crater of Mt. Augustine. Such an occurrence would be of minor significance compared to a wave generated eastwards since the west shores are sparcely populated. The eastern side of Lower Cook Inlet, in particular the areas of Kachemak Bay, have more people and pro- perty, and have.the greatest risk of damage from a tsunami. Correspondingly, those parts of the populated areas within 6 to 9 meters of mean higher high water are the areas of particular concern. Included are Port Graham, English Bay, Seldovia, Homer (particularly the Homer Spit), and other areas of development or potential development. Research is currently underway to determine whether an eruptive phase at Mt. Augustine can be predicted through an analysis of seismic activity and tidal triggering. 6. Other: See figure 9. See figure D for the proximity of Mt. Augustine and other act.ive volcanos to the communities of Cook Inlet. Reference: Kienle, J., and Forbes, R.B., 1977, Augustine -- Evolution of a volcano: Annual Report (1975-1976) Geophysical Institute, University of Alaska, (Fairbanks), p. 26-48. Pulpan, H., and Kienle, J., 1977, Seismic and V)olcanic risk studies-western Gulf of Alaska, Alaskarf OCS Principal Investigators Annual Repcrrts, 1976-1977, BLM/NOAA, p. 107. _34- D .3 15@000' d 0 7, 15' io 15 J- Areas of coastline inferred to be subject to hazard f rom Tsunami if 14p, 1000 so A@6a- t4 4r 1255 2f06 aric ko 0- J Ji J@@! -T 5 .191 2 -@,620 -0 A) I -7 ID VIL- Anchor Po or-poi P ;L@ Landmg, 4L J, V 0 Chugachik Is[ -z Be Isla 0 T .0 Olt AU(Or -- @ @L 6 Sf @,tm IN 30 i'd 6 Mall Landing Glac, /U- C @,: @-- @ y 72 SP f Y Inferred directions of travel 58 IF 300- Ismailof 15@11/ gil of Tsunami generated by @OOA al P.,int Pet III Mount Augustine r "Cash, K A C 216 LFr.Cn @11.n Are3s of coastline inferred to be subject to hazard YU 0 f rom Tsunami <f-7A@eth'lslan e GrE 210@ Bar a 'Her' 030, -S Runup of 25'to 30' in 1883 from Tsunami P -0141@ generated by Mt. Au ;nt Pogibsh Cape Wrl Dangerous" @7 VJJ RN 5a R Englis U @O N Flat. ISian Point @4, sne-, Ro@,. LOI& -@6 186 Point Ad" All 59 1 55 WN 7 rr Figure 9 P wer Cook Inlet - Kachemak Bay CO C Scale 1*250,000 C 0 C CPO) P Eliza COD so < 100 e5 A C 0 .3,00-- C7 C I I S L A N D S Anchorage A. *Geographical Location 1. Region: Southcentral Alaska, Cook Inlet 2. Latitude: 61' 131 N Longitude: 1490 53' W 3. Additional Information: U.S. Geol. Survey Quad.., Anchorage (A-8),,Tyonek (A-1), scale.1:63,360. B. Area Description 1. General geologic setting: The City of'Anchorage is located on a broad plain at the foot..of the Chugach Mountains. Bedrock beneath the plain comprises siltstones, sandstones, congloqerate, and coal of Tertiary age. Bedrock is overlain by as much as450'.meters of -unconsolidated deposits, largely of glacial origin. Of particular interest here is the Bootlegger Cove 'Clay, an estuarine.(marine) deposit of interbedded clays, silts, and sands. Marine shells from the Bootlegger Cove Clay have recently been radiometrically dated and they indicate a time of deposition of about 14,000 years ago. The deposit is now thought to have formed soon after maximum glacial advances, when world-wide sea level had begun to rise; subsequently, isostatic rebound ..(uplift) began after deglaciation of Upper Cook Inlet and eventually the Bootlegger Cove Clay attained its present position. The top of the deposit is 60 to,80.feet above mean sea level. 2. Criteria employed in identification as an APC: Failures of the Bootlegger Cove Clay during the 1964 Prince William Sound earthquake were responsible for several destructive landslides in Anchorage. Major landslide areas are the Fourth Avenue slide, the L Street slide, the First Avenue slide, the Government Hill slide, and the Turnagain Heights slide (see Plate 3 for the locations of these slides). The aforementioned areas are all adjacent to moderate to steep slopes. Evidence of older slides (now locally vegetated) along these slopes indicates that sliding occurred there before the catast rophic failures in 1964. Among the factors which probably contributed to the 1964 failures are the following: a. relatively long duration of seismic shaking; b. presence of marine clays with potentially high sensitivity; C. potential liquefaction of saturated sand horizons within the Bootlegger Cove Clay; d. presence of steep free faces. Geotechnical te.sts carried out after the 1964 failures indicate that parts of the Turnagain slide have very low shear strengths.at several depths between 28 feet and 45 feet. The surface of sliding may coincide wi-th such low strength zones. The specific areas of particular concern identified herein arethose areas where land-slides have occurred in the past, and where conditions are thought to be conducive to potential major failures in the future. (See Plate 3, ''Areas of, Potential Large Landslides".) 3. Reason for inclusion of this area as an APC: Anchorage is a coastal community and is Alaska's largest city. The city has grown remarkably since the 1950's, and some growth is likely to continue for. the forseeable future.. Land near the city center is at a premium. _ 36- Development on and immediately adjacent to the APC's identified herein should be permitted only.with a clear understanding of the potential hazard invol.ved. In particular, site-specific evaluations of proposed development sites should be carried.out by qualified engineers, and the. potential for catastroph.ic ground failure at the site addressed. other: Mt. Spurr erupted in 1953. Despite being located 140 km. west of Anchorage, up to.6 cm of volcanic ash was deposited in the city in 6 hours. The effects.were only short term, but considerable effort and money were expended in cleaning.up and attempting to stop corrosion. Health and property damage in the event of a recurrence could be minimized by advance planning of public warnings and instructions. See figure 10. References: Hansen, W.E., 1967, Effects of the earthquake of March 27, 1,964, on Anchorage,Alaska; U.S. Geol. Survey Prof. Paper 542-A. Dobrovolney, E.., and Schmoll, [email protected]., 1974, Slope stability map of Anchorage and vicinity, Alaska; U.S. Geol. Survey.Map 1-787-E. (Plate 3 of this report). Wilcox, R.E., 1959, Some effects of recent volcanic ash falls, with special reference to Alaska; U.S. Geol. Survey Bull. 1028-N, p. 409-476. Schmoll, H.R., Szabo, B.J., Rubin, M., and Dobrovolney, E., 1972, Radio- me*tric dati,ng of marine shells from the Bootlegger Cove Clay, Anchora.ge area., Alaska; Geol. Soc. America Bull., v.,33,'P. 1107-1114. -37- 152* 151 150' 149- X J650 I Boluga Mtn Mt Gerdine X 12 600 Eldutna Mt Torbert 5 X /0 600 h,ga I" Lake MT14SPURR 4/1070 Adi@e erl Area 7000 10, Anchorage hea Viest. a J.-n rh a w), aShfall 1,0 kC Tyonck 00 61,00, Z' Black Peak 6-109 Portage V 0 EXPLANATION Double Peak Active or potentially active volcanoes Gilpatrick Mt* X 496.?9 Nonvolcan;c peaks 1 Kenai 0 10 20 30Miles Volcano 0 1.0 29 30 Kilometers '.197 Figure 10: Map of area of ashfall from eruption of Mt. Spurr, 1953. From Wilcox, (1959). c Igoe er 0 C1, r;, a K Cena Knik River Outwash Plain A. Geographical Location 1. Region: Southcentral Alaska., Upper Cook Inlet 2. Latitude: 61' 29' N Longitude: 149' 16' W 3. Additional Information: U.S. Geol. Survey-Quad. Anchorage, scale 1:250,000. B. Area Description 1. General geologic setting:@ Lake George.has been in recent years the largest glacier dammed.lake in Alaska, attaining a maximum area of '70 sq. km. The lake forms by glacier advance, and closing of the outlet channel by the ice, and fails by erosion and/or hydrostatic uplift of the ice. It drains into the Kn.ik River, through a gorge along the margin of Knik Glacier. From 1918 through 1966, except for 1963, it flooded Knik River annually. From 1949 through.1961 there was a significant increase in.the peak discharges. Due to a thinning of the ice at the glacier terminus, the peak discharges from 1962-1966 were lower. The failure usually occurred in July or August. Since 1966, Knik Glacier has failed to form an ice dam and the lake has not filled. At peak times of flood, the discharge in the Knik River has been in excess of 12,000 cubic meters per second, and has risen as much as 7 meters. 2. Criteria used in identification as an APC: Although Lake George last emptied in 1966, a series of positive ice balances may stimulate Knik Glacier to advance and dam the lake again. If so, then outburst discharge in the Kni.k River would cause an extreme flood hazard along the Knik River flood plain. 3. Reasons for identification of this area as an APC: The Knik River vicini.ty is among one of the fastest growing areas in Alaska, and contains the major arteries of trade from Anchorage to the Interior. This area will continue to grow in the future, and such expansion should take into account the possible dangers of a flood of the magnitude that the Knik Glacier is capable of producing. It should be emphasized that the potential for renewed advance of the Knik Glacier is presently uncertain. 4. Other: Because of the spectacle of the breakout, the area has been.proposed as a natural landmark by the National Park Service several times. U.S. Army Corps of Engineers may begin detailed study in 1978 to precisely define the floodplain limits.along lower Knik River. See.figure 11. Reference Post, A., and Mayo, L.R., 1971, Glacier da mmed lakes and outburst floods in Alaska, U.S. Geol, SLII-VCY MI)p IIA-1155. -39- 149@60'- ee q 7, A- Kv, " lk X w" a V) /F Co ent urE 'A @, n"-j -- Ula d0lP Inferred Iml PK, 3@ of flo zone 0i @J, )L ft Asq. [Breakout zone rk, Inner Par q, @kv,,,- 11\1 Xlll@, Law Ge 601orly Pt 610 3C -4- j Figure I I IK RIVER FLOOD PLAIN 1062 --undaries approximate) 000 Scale 1 250) L 4 wtv Drift River Delta A. Geographical Location 1. Region: Southcentral Alaska, Cook Inlet 2. Latitude; 60' 35' N Longitude: 152' 28' W 3. Additional Information: U.S. Geol. Survey Quad., Kenai (B-7, C-6, C-7), scale 1:63,360. B. Area Description 1. General geologic setti ng: Redoubt Volcano is an active volcano in the chain of volcanos along the 'mountains bordering the west shore of Cook Inlet. It is over 3,000 metershigh and is covered in glaciers and snow. During an eruption beginning on January 24, 1966, a large amount of water from snow and ice melt and mud was released and descended from the.summit crater. These waters- then proceeded down.th e nearby Drift River. 2. Criteria employed for identification. as an APC.: Recurrent explosions and turbulent clouds have triggered flash floods in Drift River from the sudden melting of the glaciers on.the mountain. Redoubt Volcano is considered active and is capable of renewed activity at any time, producing more flooding. 3. Reason for inclusion of this area as an APC: A major petroleum pipeline terminal and tank storage farm which serves several of 'the oil fields in Cook.Inlet,, is located at the mouth of the Drift River. It was built after the floods in 1966, and was engineered for such a contingency. However, Redoubt Volcano could heat up and produce flood waters of equal or greater magnitude than those produced.in.1966. 4. Other: See figure 12. Reference: Post, A., and Mayo, L.R., 1971, Glacier dammed lakes and outburst floods in Alaska, U.S. Geol. Survey Map HA-455.. A % 0 Q) terred lirr f I ood zoi IV 950 Boo 3(@,- 01 " C)OO 00 "00 FqA Lak@ 1000- 36 M O/Z 66 nt 3025 is 6 12 t 30 /01 .......... 5 . . . . . . . . . . . . . . . . . . . . . . . @00 074 t% A Y Figure 12, DRIFT RIVER DELTA (Boundaries approximate)' Sc6le 1'250,600 2@K land AS -2000 Kod i a k A Geographical Location, 1. Region: Southcentral Alaska. 2. Latitude: 57' 471 20`11 N Longitude: 152' 471 1011 W 3.- Additional Information: U.S. Geol.. Survey Quad., Kodiak (C-1, C-2, D-1, D-2), scale 1:63,360. B. Area Description I.. General geological setting: The town of Kodiak sits upon bedrock composed of marine sedimentary rocks of probably Cretaceous age which have been complexly deformed and intruded by granitic rocks. Surficial deposits are generally thin and discontinuous, although parts of the Women's Bay area are underlaid by thicker glacial or alluvial deposits and artifical fill. The area south of Kodiak to Ugak Bay consists of poorly. consolidated upper Tertiary marine sedimentary rocks which have been gently to moderately folded and which overlie the older rocks. Most of the coast consists of,rugged rocky bluffs. .2.. Criteria empl-oyed in identification as an APC: Kodiak and the surrounding area suffered extensive property damage and 18 lives were.lost as a result of a tsunami generated by the earthquake of March 27, 1964. There are no other reports of tsunamis striking the area in historical times. The runup level of the waves varied according to I oca I i.ty,, topography of the offshore bottom and, other factors. Maximum runup is some unihabited areas of the island was in excess of 15 m. , and runup at the town of Kodiak was in excess of 6 m. causing extensive damage to the waterfront. 3-Reason for inclusion of th is area as an APC: Kodiak is the focal point and economic hub for fishing, logging and cattle ranching activities for the area and surrounding islands. These industries constitute the economic base for the region. Kodiak Naval Station is located 10 km south of the city and provides.substantial revenue to the area. Any interference with these activities could have an adverse effect on the Alaskan economy as a whole. 4. Other: The Army Corps of Engineers has identi fied the Shakmanof Cove, Kizhuyak Point area as being One of the few areas in the Kodiak Region which has suitable @mounts of'rock for use as any and all types of construction materials. Sound durable rock of all sizes could be quarried and excellent quarry operations could be developed with a minimum of effort. (G. Greely, pers. comm. 1977) Much of Kodiak Island is a National Wildlife Refuge. .'See fioure 13. Reference: Kachadoorian, R., and Plafker, G., 1967, Effects of the earthquake of March 27, 1964 on the communities of Kodiak and nearby islands, U.S. Geol. Survey Prof. Paper 542-F, p. FI-F41 43- itt e 10 Iphin Pt 1520 3C 0 A ft 0 1;'@U)Id'ek I T H reewss 0 Sni Pt .0 rtn Cap 10f I0(( Site of potential w 0 0 0 riprap development apad 110f 00 Sma 11 nd, VOO ent Pt t 60 08 'T ovati Pt ABM,, u ni Pt 5 09M. k Rk Kizh.& tc e hag ks ne, Pt -L@g Pt a, y -e ra@ t le Off 500 eregrebni o@n 2 1 0 harati P nation ;bl YW a Millill t11 Mson (Milliams Reef, 10 et pe S10 Tfdi*Rk, Jr-11 If wmill FIt 300 ifa P J 4 Bay ig Isla ing Bluf 0 0 0 V f Rko U9 0 0 57045 PO INIAK e@ - 0 f 'Pt BAY 00 0 CIO op , 0 Oompback 0 @e'Wjesoki A 00 0 02 ka Area subject to damage@ f S 0 from Tsunami 00. Ut Qn ak I -b mudK @O pe 0- J. Ville 4, Q) 1654) ,- @uel Pt R 18 W, I21yP .0/6- Delt rea.4. V C-1 A-0 @t@rop Shark F g L! re 13 ng 'KODIAK & VICINITY' gs from Plaf ker a Kochadoorian DC1- a (1966 R 20 W ale 1:2501000 CS C Scotch Cap, West End of Unimak Island A. Geographical Location 1. Region: Aleutian Islands 2. Latitude: .54' 45' 14 Longitude: 165* 00' W 3., Additional Information: U.S. Geol. Survey Quad., Unimak, scale 1:63,360. B. Area Description 1. General geological setting: The area of particular concern is located on the westernmos-t end of Unimak Island. The area to the north and east rises sharply from the coastline and culminates in Faris Peak 1600 m. Unimak. Island is basically composed of Quaternary basal.tic and andesitic lava flows and pyroclastic deposits. Both Westdahl and Pogromni are volcanos of recent origin. 2. Criteria employed in identification as.an APC: The western end of Unimak Island has been hit at least twice in very recent times by tsunamis of considerable size. On April 1, 1946, a tsunami struck which demolished the Scotch Cap light house and killed five people. This wave was generated by a submarine earthquake of magnitude 7.4 located about 28O.km to the southeast of the island. A runup of about 30 m. was recorded. Again on March 9, 1957, an earthquake of magnitude 8.3 occurred to the southeast. Although lighthouse personnel reported no damage occurred, a runup of 15 m. was estimated. This wave might have been generated locally by a marine landslide since its arrival was too early for a major tsunami. 3. Reason for incl,usion of this area as an APC: Although the entire southern coast of Alaska is susceptible to tsunamis, only the areas of cultural activity where significant property damage or.death have been recorded are designated as APC's. Thus, much of the Aleutian Islands coastline may be prone to damage by tsunamis. Only the areas where documented sig- nigicant runups and where property damage has occurred or could occur are included here.. 4. Other: The area is included in a National Wildlife Refuge. Also, Unimak Pass is a significant break in the Aleutian Island chain and might be important.to shipping, in which case the maintenance of,a lighthouse could be necessary. See figure 14. Reference: Cox, D.C., and Pararas-Carayannis, G., 1976, (rev.), Catalog of tsunamis in Alaska,.World Data Center for Solid Earth Geophysics, NOAA Report @SE-1, P. 1-43. -45- M Pm M V 000 T 63 5 0 i s he Jr @,6 Id era BOO R 103 w U-) 434 0 i'@@ @-F E Ri A Beta @J 'G E Pt. catar act Su NBM Raven' t C, 0. 64 5 -5 _:@x2dioc T ighthou h Lig 0' L D LAI 0,0 Ca@e Saric *- 1-z lio e Iea IF r6rn n I -, i 4 r-ory z > V T 1.5 \ 'T 65 S > )> @and 54 '6%Faris Peak ----:@@118-@)Westdahl Aeak 0 -50 64o 3d- Se n n @btt n @7 pe Lutke + 60 + ./T 66 S T 66 S U /000 F1 ? ontc Cabin H 411 t;@-Cap. hp t @- I -2:D _-60 R 102 W 0 by ++ ++ Se arie 1946, 100' runup, 1946 (Tsunami) J@ 50' runup, 1957 (probably caused by marine landslide) Figure 14 IDirection of wave] SCOTCH CAP UNIMAK ISLAND @E- ,:by 19:4 ]6@ Boundary approximate Mag.74 earthquake 175 miles to SE in 1946 Data from Cox 8 Pararas-Caroyannis(1976' Scale 1'250,000 Shemya Island A. Geographical Locat-ion 1. Region: Aleutian Islands 2. Latitude: 520 431 2011 N Longitu de: 1740 07' 00" E 3.* Additional Information: U.S. Geol. Survey Quad., Attu, scale 1:250,000. B.. Area Description 1. General geologic setting: The area of particular concern is located 6 km east south east of Attu Island, on the westernmost extention of the A.leutian Island Chain. Shemya Island is the largest of the Semichi Islands. It has little relief. The island is composed of Tertiary or Cretaceous-sedimentary rocks, including pyroclastic,deposits, lava flows and minor pillow lavas., 2. Criteria employed in identification as an APC: Shemya Island has been hit by at least one tsunami in recent times. On Febuary 4, 1965@an*earthquake of magnitude 7.8 occurred about 360 km. east south east, causing waves of about 10 m. to strike the island. The only reported damage was flooding to a warehouse. 3. Reason for inclusion of this area as an APC: Although the tsunami of 1965 did not cause considerable damage, tsunamis may well strike in the future. Jhe USAF has establis'hed a base.on the island, and there is a corresponding higher density of personnel and property on Shemya.Island than in other areas in the Aleutians. Thus, the potential for property damage or loss of life there @in the event of a major tsunami does exist. 4. Other: As previously mentioned, Shemya Island is presently being used as an air base by the USAF. See figure 15. Reference: Cox, D.C., and Pararas-Carayannis, G.., 1976, (rev.), Catalog of tsunamis in Alaska, World Data Center for Sol'id Earth Geophysics,.NOAA Report.SE-l, .p. 1-43. -47- FOC I Dint qead Alaid Head 662.&L-e4rLon Uli Alaid Island Jak A'57 0 --4f 520 45' %S@ Shernya Island j OP7 A3. Nizki Island H.-@hejit. AY @3 @3r u n u @pl n 5 D S Inferred direction of wave travel Magnitude 78 earthquake 225 miles ESE in 1965 S L A N D S Figure 15 "i Krugloi Point SHEMYA ISLAND Patricia Po,n*,7'%p VABIM@ Krug VAE , t @@, h, 337- Pat Data from Cox & Parcros-Carayonnis (1976) 32, Scale 1:250,000 Pribilof Islands (St. George and St. Paul) A. Geographical Location I. Region: Southwestern Alaska, Bering Sea 2. Latitude: 57* N Longitude: 170' W 3. Additional Information:. U.S. Geol. Survey,'Quad., Pribilof Islands, scale 1:250,000 B. Aeea Description 1. General geologic setting: St. George Island is composed of volcanic rocks (lavas) erupted mainly between 2.5 and 1.0 million years ago. St. Paul Island is mainly lavas erupted in the past 300,000 years. Both islands are extensively coverd by wind-blown silts and sands, partly stabilized by veg- etation. St. George Island has been glaciated, St. Paul Island has not. 2 Criteria employed in identification as a,n APC: The -islands have experienced volcanic eruptions as recently as 10,000 years ago (St. Paul Island), and faults disrupt relatively young volcanic rocks there. Consequently, the islands must be considered to pose hazards to any potential onshore'and offshore developments, due to (a) direct contact with lava, bombs,* or ash, or secondary slides, and locally generated tsunamis, in the event of renewed volcan.ic activity, and (b) seismic shaking, tsunamis, and ground breakage along faults which may move in future earthquakes. 3. Reason for inclusion of this*area as a APC: Sedimentary basins of'the Bering Sea are thought to have considerable oil/gas potential. A federal lease sale in the Bering Sea is now scheduled for December of 1981. The Pribilofs are logical candidates for siting of logistic bases, and for location of a pipeline terminal in the event that producible hydrocarbons are found. 4. Other: The Pribilofs presently constitute a federal game preserve. See figure 16. 5. Source of.Data: Hopkins, 1976, Fault history of the Pribilof Islands and its relevance to bottom stability in the St. George Basin: Alaskan OCS Principal Investigators' Annual Reports, NOAA/BLM, p. 41-67. _49- S E Northeast Fit W'ebster L Volcanic vents North Fit Major faults Lincoln Big Bighi 4220100t Lake Hill Sheep L 'R'\Us HilL 0 e0goslof Poiovwia Hill Ernahnuhto Bluffs 10665 0 590 Hil* Lake V70 Cone Hill Southwest Halfway Flt Fit 40 s L Tonki Pt Zapadn; P@ '130'V - Englis, Tolstoi"( 0 Lukanin Bay ,,@ 0.,V r. ale Pt Volcanic vents Pt t Paul Z010toi @ @y Major faults Ree; Pt ST. PAUL ISLAND *Sea Lion Rock Otter ls@anc St. George Island St. Paul Island 288 39 miles SE 39 miles 170030' + 57000' Dalnoi Pt uskaralogh Pt Norih Anchorage 0 F@mt 81ull St. George Fox CastI6 , 157/ 101@7 Tolstoi Pt Rush Pt A tk(t 1, al 9 0679, JSL;j L@t,n Pt Zapadn i -\1 @-* I ",- Bay 0 "i3arden Cove [,!fl Iflu; k@d [0,11, ST. GEORGE ISLAND - '@- --- 1-j U(n.inangul.1 Wulf, Ca%cade Fit Figure 16 0 al 9 PRIBILOF ISLANDS 169030' Data from Hopkins(1976) + 560 30' Potentially active faults &volcanic vents Scale .1'.250,000 Cape Krusen@tern to Cape Th ompson A. Geographical Location 1. Region: Western Alaska, Chukchi Sea 2. Latitude: 67* 5' to 68' 10' N. Longitude: *163'-30' to 1660 w. 3. Additional Informa tion: U.S. Geol. Survey Quad., Noatak, Point Hope, scale 1:250,000. Area Description 1. General geologic setting: Cape Krusenstern is an accreted beach-ridge plain which separates Krusenstern Lagoon from waters of Kotzebue Sound. Much of the sand and gravel comprising the plain has been carried from a northern source, ..possibly as far as Cape Thompson (105 km The oldest ridges formed at least 3500 years ago, and possibly as much as 4500 years ago (ages are inferred from archeological evidence and from morphology and elevations of the ridges). The shore between Cape Krusenstern and Cape Thompson consists chiefly of barrier bars backed by lagoons. Erosional bluffs are cut in bedrock or gravel (Cape Thompson to Kisimilok Mountain, and at Battle Rock) and in silt and sand (locally between Rabbit Creek and Krusenstern Lagoon@ Elsewhere, the coast is low-lying and devoid of bluffs. 2. Criteria employed in identification as an APC: Detailed work by t'he U.S.G.S. at Cape Krusenstern shows that the beach ridge plain has experienced short periods of erosion at various times throughout the 4500-year period of net accretion. Such erosion might have been caused by shifts in the d1rection of storm winds, or by interruptions in the supply of sediment. Availab*le evidence suggests that much of the sand and gravel of which the plain is constructed was delivered by littoral drift from sources as far to the northwest as Cape Thompson. Consequently, coastal activies and construction (such-as .jetties) between Cape Krusenstern and Cape Thompson could interrupt the littoral drift to the extent of causing erosion at Cape Krusenstern. 3. Reaso.n for inclusion of this area as an APC: The Cape Krusenstern.beach ridge plain has been occupied nearly continuously for the past 4500 years and con- stitutes a record of Arctic archaeology of major importance. 4. Other: The area is proposed for classification as.a National Monument. See figure 17. Reference: Hopkins, D.M., 1977, Coastalprocesses and coastal erosional hazards to the Cape Krunsenstern archaeological site; U.S. Geol Survey Open-fi le Report 77-32 p. 15. -51- 7, @A -0 32 J" -4- 1617 0 _jo VA Fiats 7 Coast stable 37Y 2,000 years for--last IVA @T, Q,) 1/44 -837 A- Longshore - ----- drift @Iglo.?6 50 M 670 30'.' Imik 55" R7 Lagoon Coast retreated 4 __q T 2 0.5 km. in 3,500 years VAB t do. KO 78 Lagoon T 23 IN VAE3M Wor@de let Kiligmak In Cab' 04- (7: v Coast retreated .25 km. in 3,500 years Tasaychak Lag- Shelter Cabin + 48 U @j 5!, F Coast retreated Ca. 0.6 km. in 3,500 years- Talikoo vim., T 20 IN Krusenstern NAB rchaeof IC Site I@i I a k "Blu Figure 17 Coast has prograded Cabir, VAB n1yak up to 3 km. .64 CAPE KRUSENSTERN in 4,50.0 years Data from Hopkins, .-1971 90 Scale 1'.250,000. 42 Wainwricht and Barrow and Vicinity A Geographic Location 1. Region: Northern Alaska, Chukchi Sea 2. Latitude: 70* 40' N Longitude: 160* W 3. Additional Information: U.S. Geol. Survey Quad., Wainwright (C-2), Barrow (B-4), scale 1:63,360. B. A.rea Description 1. General geologic setting: The land surface in the APC is part of the Arctic tundra plain. Frozen permafrost is present nearly everywhere at shallow depths on land, and probably occurs beneath the sea bottom to some distance offshore. Deposits at or near the surface ar@ older interbedded marine and terrestrial sands and gravels,,and beach deposits along the present shoreline. 2. Criteria employed in identification as an APC: The entire coastline from Icy Cape to the Canadian border is recognized as one of relatively high rates of bluff retreat by thermal erosion and wavecu.t. Coastlines are retreating faster in this area than in most pbrts of the Chukchi Sea coastline. Erosion occur chiefly during the late summer and fall storm surges, when winds and ii-r pressure cells can combine to raise sea level above mean higher high waterline. Such a storm surge in 1975 was responsible for flooding from Icy Cape to Peard Bay; the'inundation locally was the greatest recorded in this century. In addition to erosion and storm surge flooding, the coastline from Icy Cape to the Canadian border is thought-to be underl'ain by bonded permafrost at shallow depths beneath the seafloor, from the beach out to water depths estimated to range from 2m to 30m. Bonded permafrost was not found beneath the bottom of Elson Lagoon at Barrow, but preliminary work suggests that permafrost is likely to be present beneath.parts,of Wainwright Inlet. 3. Reason for inclus ion as an APC: Wainwright and Barrow are the largest coas.tal communities withinflaval Petroleum. Reserve A. Should producible hydrocarbons be found in the reserve, then either or both villages could be considered @as potential sites for logistical bases or even storage depots. Coastal erosion flooding and permafrost are obvious constraints to be considered in develop- ment of facilities at the coastline. Other: NOAA/BLM sponsored research is continuing in,the Chukchi-Beaufort coastal area, and more definitive publications should be available by 1978 or 1979. See figures 18 (Wainwright)'and 19 (Barrow). Reference: Hopkins, D.M., 1976, shoreline history of the Chukchi Sea as an aid to.predictin4. offshore permafrost conditions; Alaskan OCS Principal Investigators' Reports, NOAA/BLM (July-September 1976),.p. 213-218. Rogers, J.C., Gedney,L.D., Shapiro, L.H., and VanWormer D., 1975, Near shore permafrost in the vicinity of Point Barrow, Alaska; Proceedings of the .Third International Conference on Port and Ocean Engineering under Arctic Conditions, Univ. of Alaska, Fairbanks, P. 1071-1082. -53- .166- 00' kpilgok 10 '@A 1 70040' Figure 18 WAINWRIGHT & VICINITY,- Data from Hopkins (1976Y 1-Z Scale 1:63,360 57 j 13,1 T@ /Z 2@. j Inferred zone of 21 22 severe coastal erosion 'Vainwright - '2 D/ 7 r t Poln collie 3 4 Point Marsh 12 15 M 1 14 1q( 2 INL Tutolivik W A N W R G H. T y. '7" Kil-uk Point Sigeakrukj Point t X _/17 K. 10 13'@ c, 2'1 2-1 OUC]c' C2 'A 15@0 40' Figure' 19 BARROW*& VICINITY Data from Rogers & others (1975) Scale 1:63,000 I0 B 47 4,@ 10 oat .1- 0@@k North 710 2C 22 Salt 3 24 Imikpuk Lagool? y -e F-, Site Lak Midd q 25, 90 8 26 Salt 0lit Salt X. Inferred zone of severe ---------- I_ NO shoreline erosion. 13 2, >_ 33@ 3 36 31 23 N sa 017 '37 22 --Will R4e,s "it; Me, ;2' 3 9 2 7 IV 12 C4 4 '60 X 13 18 6 15 41\ 13 D 4 Prudhoe Bay and Vicinity A. Geographic Location 1. Region: Northern Alaska, Beaufort Sea 2. Latitude: 700 20' N Longitude: 148* 25' W 3. Additional Information: U.S. Geol. Survey Quad., Beechey Point (B-4), scale 1:63,360. B. Area Description 1. General geologic setting: The land surface around Pr udhoe Bay is part of the North Slope tundra plain. Interbedded marine and alluvial sands and gravels underlie the area. Organic matter (tundra), active river courses, and active and stabilized wind dunes comprise the majority of the land surface features. Lake basins which have originated by thawing of the ubiquitous permafrost comprisethe remaining features. Up to 2 meters of sea ice freezes annually offshore of the area ("fast ice"). 2. Criteria employed i n identification as an APC: The location of the channel followed by barge tugs into.Prudhoe Bay (and now to the gravel causeway constructed by ARCO in 1975) has shifted relative to shoreline by as much as 175m between 1950 and 1976. Mean depth of the channel (minimum depths entering Prudhoe Bay were between @ and 2 m. in 1976) may have increased slightly. However, shoaling of the channel is reported during the open water season (July to September). Nearby, Stump Island has also shifted southwest ward (relatively shoreward) and grown in .area. Exposed.shoreline from Point McIntyre east has been eroded (primarily thermal e.rosion of permafrost tundra) at an average rate of I m/yr.,but locally by as-much as 3 mlyr., during the period 1950 to 1970. Furthermore, the.offshore area i.n and around Prudhoe Bay is everywhere thought to be underlain by ground below O*C. Ice-bonded permafrost is thought to occur Just below the sea-bottom in areas contacted by annual sea ice (that is, less the 2m depths) and at.progressively greater depths further seaward of the 2m isobath. Overice flooding and spring breakups on the larger rivers (such as the Sagavanirktok) are potential hazards, but no final studies have yet been published on spectfic rivers within this APC. 3. Reason for inclusion of this area as an APC: Petroleum activity in the vicinity of Prudhoe Bay is intense. Freight barges used the bay entrance channel a1most exclusively for the past 8 years, and now make heavy use of the ARCO causeway for offloading. The short open water season (normal.ly July through. September) and expense of constructing offloading and storage facilities, imply that changes in channel configurations and temporary interruptions in barge access can have serious consequences. -It has been suggested that the Prudhoe Bay entrance c 'hannel is scoured by sub-ice currents during freeze-up, and begins to infill during open water. Thus, the channel may not be irreversibly filling up, at least in the foreseeable future. Future coastal activi Lies any- where in the Beaufort Sea must allow for shoreline erosion-and natural changes in offshore bathymetry as well as potentially adverse effects of the activities themselves on the rates of such changes. Also, engineering design and con- struction must allow for potentially adverse effects of melting (bonded) permafrost, especially settlelment and subsequent niaterial-.erosion, both onshore and offshore. -56- 4. Other See figure 20. References: Barnes, P., Reimnitz, E., Smith, G., and Melchior, J., 1977, Bathymetric and shoreline changes, northwestern Prudhoe Bay, Alaska; U.S. Geol. Survey Open-Tile Report 77-161. Osterkamp, T.E., and Harrison, W.D., 1976, Subsea permafrost at Prudhoe Bay, Alaska; drilling report: Univ. Alaska Geophys. Inst., Sea Grant Report No. 76-5. Hopkins, D.M., 1976, Offshore permafrost studies, Beaufort Sea; Alaskan OCS Principal Investigators' Reports, (July-September, 1976), NOAA/BLM, p.'83-100. -57- 1460 30' @g I n d ?o ASI stump 4 Island 700 25' swm@p 2 Point Storkersen Figure 20 10 PRUDHCIE BAY & VICINITY. bata' from Smitha Melchoir (1977) Scale 1'.63,360 Point McIntyre ? 04D D 2@61%k till Probable ione of shallow bonded seaf loor permaf rost 'Site of Arco dock OT T Zones of severe coastal er-'-1 -2@ th P,.dhoe p J1 ZL 0, 9e@ 0 0 4 b- *'Ai 0 oo 4t, 626 J7 3 Nl@ 00 "It I % 0 0 6 35 6 S P -7 L 3 3 to 0 6k OOE -D, S@, PRO -12@ W qz - S, D4 44 @4@ 9 0 1 0 06 .9 2 Wi- 8 Pao, -9 17- 4 P@ -@D t@ AN 24 24 20 Z, zf NO SERVICES CTA LIBRARY 3 6668 14110079 4 ZONE MIER AA COASTAL