The Alaska Earthquake March 27, 1964 Regional Effects
Shore Processes and Beach Morphology
GEOLOGICAL SURVEY PROFESSIONAL PAPER 543-J
~~~m~~~~~~ll'ilir- DENVER 3 1819 00086468 2
THE ALASKA EARTHQUAKE, MARCH 27, 1964: REGIONAL EFFECTS
Effects of the Alaska Earthquake of March 27, 1964 On Shore Processes and Beach Morphology
By KIRK W. STANLEY
The effects of tectonic uplift and subsidence along 10,000 miles of shoreline, and the practical meaning of those effects
GEOLOGICAL SURVEY PROFESSIONAL PAPER 543-J
APR 7 1969 APR 11 1991 UNITED STATES DEPARTMENT OF THE INTERIOR
STEWART L. UDALL, Secretary
GEOLOGICAL SURVEY
William T. Pecora, Director
UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1968
For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402- Price 45 cents (paper cover) THE ALASKA EARTHQUAKE SERIES
The U.S. Geological Survey is publishing the re sults of its investigations of the Alaska earthquake of March 27, 1964, in a series of six Professional Papers. Professional Paper 543 describes the re gional effects of the earthquake. Other Professional Papers in the series describe field investigations and reconstruction and the effects of the earthquake on communities, on the hydrologic regimen, and on transportation, utilities, and communications. CONTENTS
Page Page Abstract______J1 Coastal features and earthquake Introduction______1 effects -Continued Shorelines of the earthquake-af- Coastal erosion and movement fected region______2 of material-Continued Coastal features and earthquake Longshore material move- effects______3 ment ______J15 Beaches______3 Upslope material move Changes in profile and ment______17 gradient______3 Biologic effects of shoreline changes ______17 Minor beach features_____ 5 Low-water features______6 Fish______17 Shellfish ______18 Modern beach ridges_____ 7 WildfowL______18 Ancient beach ridges_____ 10 Effects on property and manmade Stream-mouth changes______10 structures______19 Submergent areas______10 Submergent areas______19 Uplifted areas______11 Emergent areas______19 Coastal erosion and movement Legal problems______19 of materiaL ______12 Need for further studies______20 Erosion______12 References cited______20
ILLUSTRATIONS
FIGURES
Page Page 1. Index map of south-central Alaska showing coast- 9. Photograph of gullying and sloughing caused by lines affected by the earthquake ______vr headward stream erosion, Copper River Delta_ .J12 2. Diagram illustrating beach feature ______J3 10. Photograph of eastern shore of Cook Inlet showing 3. Photograph of sharp break-in-slope on shingle undercutting and sloughing of bluffs caused by beach ______4 subsidence______13 4. Sketch of changes of beach configuration in sub- 11. Photograph of bluff erosion at Kenai______13 mergent areas ______5 12-14. Photographs of timber seawall on Homer Spit: 5. Photograph of deposition of material on backslope 12. As constructed______14 of frontal ridge ______8 13. Damaged, 6 months after construction____ 14 6. Aerial photograph of barrier beach at Breving 14. Almost completely destroyed by waves, 16 Lagoon, Seward Peninsula ______9 months after construction______15 7. Photograph showing undercutting and sloughing 15. Photograph of cobble-filled wire-mesh fence, of bluffs, Cook Inlet ______9 Larsen Bay, Kodiak Island______15 8. Oblique photograph of new land created by tec- 16. Profiles of updrift and downdrift fill of grain at tonic uplift, Copper River Delta ______11 Homer Spit______16 v 144' 156• 64' .., 64° .";;f
s
EXPLANATION
Approximate line of zero land level change (after Plafker, 1965) 0
50 0 50 100 150 MILES
56'15' 56'15' 156• 144'
1.-·South-central Alaska showing coastlines affected by the earthquake. Land to left of zero land-level change was generally lowered; land to right was raised.
VI THE ALASKA EARTHQUAKE, MARCH 27, 1964: REGIONAL EFFECTS
EFFECTS OF THE ALASKA EARTHQUAKE OF MARCH 27, 1964, ON SHORE PROCESSES AND BEACH MORPHOLOGY
By Kirk W. Stanley 1
ABSTRACT
Some 10,000 miles of shoreline in were altered or destroyed on submerg Streams were lengthened in the emer south-central Alaska was affected by the ence but began to reappear and to gent areas, and down cutting and bank subsidence or uplift associated with the stabilize in their normal shapes within erosion have increased. great Alaska earthquake of March 27, a few monthH after the earthquake. Except at Homer and a few small vil 1964. The changes in shoreline processes Frontal beach ridges migrated shore lages, where groins, bul,kh€1llds, and and beach morphology that were sud ward and grew higher and wider than ,cobble-filled baskets were installed, denly initiated by the earthquake were they were before. Along narrow beaehes there has been little attempt to protect similar to those ordinarily caused by backed by bluffs, the relatively higher tihe postearthquake shorelines. The few gradual changes in sea level operating sea level led to vigorous erosion of the structures that were built have been over hundreds of years, while other bluff toes. Stream mouths were drowned only partially successful because there more readily visible changes were sim and some were altered by seismic sea was too little time to study the habits iLar to some of the effects of great but waves, but they adjusted within a few of the new shore features and to design short-lived storms. Phenomena became months to the new c-onditions. appropriate protection measure~. Emer In the uplifted areas, generally around available for observation within a few gence of large areas that were once hours which would otherwise not have Prince William Sound, virtually all below water and permanent submer been available for many years. beaches were stranded out of reach of gence of once-useful land areas have led In the subsided areas-including the the sea. New beaches are gradually de shorelines of the Kenai Peninsula, veloping to fit new sea levels, but the to many problems of land use and Kodiak Island, and Cook Inlet-beaches processes are slow, in part because the ownership in addition to the destruction tended to flatten in gradient and to re material on the lower parts of the old or relocation of wildfowl, shellfish, and cede shoreward. Minor beach features beaches is predominantly fine grained. salmon habitats.
INTRODUCTION
One of the strongest earthquakes lowered as much as 71;2 feet and by the earthquake are included, ever reported occurred in Alaska 25,000 square miles was raised as the shoreline within the area ex on March 27, 1964, at 5:36 p.m. much as 33 feet (Plafker, 1965, ceeds 10,000 nautical miles. Alaska standard time. The epi 1967). The coastlines affected by Certain changes in beach forms center was at Unakwik Inlet in the earthquake are shown by occurred as a result of relative Prince William Sound (fig. 1). figure 1. changes in sea level caused by up The magnitude of the main shock Definite limits of the coastal area lift or subsidence of the land dur was 8.4-8.6 on the Richter scale of Alaska affected by the earth ing the earthquake. These changes (Wood, 1966). The area of land quake have not been determined. were abrupt and thus cannot be and sea bottom affected by the Most authorities, however, agree unconditionally compared to a gradual change in sea level, but earthquake is at least 70,000 square that it is bounded by Yakataga they did provide much informa miles and may exceed 110,000. (just southeast of the area shown tion regarding normal shore proc Forty thousand squa.re miles wa8 in figure 1) on the east and the Kodiak group of islands on the esses. Because sea-level changes southwest (Plafker, 1965). I£ all were not only abrupt but also 1 Geologist, Anchorage, Alaska : formerly Tidelands Supervisor, Alaska Department of the shoreline irregularities of the permanent, months were afforded Xaturnl Resources, Division of Lands. mainland and the islands affected for observations, which other- J1 J2 ALASKA EARTHQUAKE, MARCH 27, 1964 wise-as during storms-would problems. These limited observa available. Descriptions of coastal have been limited to hours or at tions do not reflect all conditions erosion primarily involve exam the most several days. and processes that occurred within ples along Cook Inlet because (1) No attempt is made in this paper the area affected by the earth much of the shoreline there is erod to present a detailed description quake, but they do provide a basis ing and ( 2) the area is more of changes in beaches throughout for understanding the general densely populated than elsewhere. either the submergent or emergent processes that occurred. The earthquake not only caused areas. A study of this type might The chief objective of this report physical changes which have left have provided some interesting and descriptive material, but, con is to compare pre- and post-earth their marks upon the beach; it also sidering the great distances and quake processes. For this reason, had certain significant economic the general remoteness of much of Homer Spit is used as an example and legal consequences. These so the shoreline involved, such a for much of the descriptive mat ciological effects have an intercon study would have been impractical. ter; it happens to be one of the nection with the physical effects This paper is therefore restricted few places :for which consider and are considered worthy of to descriptions of specific areas and able preearthquake information is mention.
SHORELINES OF THE EARTHQUAKE-AFFECTED REGION
The line of zero land movement, formed in part of outwash de posed of medium to coarse shingle. (fig. 1) trends southwest from the posits from the Bering and other Sandy beaches and constructional epicenter on Unakwik Inlet at the large glaciers. Westward from the costal forms occur along the head of Prince William Sound, Copper River Delta the shoreline heads of bays, however, and well along the east shore of Kenai Pe is glacially carved and is highly developed sand-shingle beaches ninsula, to Kodiak Island. West irregular, deeply incised, and tens of miles in length are present of this line the land subsided; to fringed by numerous offshore along the south,yesternmost part the east it was uplifted. Anoma rocks and reefs. The offshore area, of the island. lous areas of submergence, particu particularly between the mouth of Along the southern Kenai Pe larly along deltas and at the heads the Copper River and Cordova, is ninsula and the western part of of bays, occur in both regions and shallow and has numerous shoals, Prince William Sound, the shore were caused by compaction and barrier islands, and spits. Active line resembles that of Kodiak Is settlement of sediments. Compac glaciers occupy the heads of many land in its irregularity, although tion of sediments in the uplifted bays in the region, particularly in bayhead depressions and subma area reduced the overall upward Prince William Sound. rine rock ramparts at the bay change in some localities; compac Along Kodiak Island the shore mouths are less well developed. tion in the subsided areas accen line is characterized by fiords in However, the presence of active tuated submergence. classic forms. The bays, particu glaciers along the shoreline indi The landmass bordering the larly along the Shelikof Strait side cates that many of the indenta coastal area affected by the earth of Kodiak Island, have deep de tions are true fiords. Here also the quake is mountainous, and both it pressions at their heads and sub walls of many of the bays are and the shoreline are characterized marine threshholds of either rock steep, and cliffs are more numerous by glacial or periglacial features. or unconsolidated material at than along Kodiak Island. N ar The shoreline from Yakataga their mouths-a feature that, ac row, relatively steep beaches con northwestward to the Copper cording to Guilcher (1958, p. 160), sist predominantly of shingle. River Delta is characterized by denotes a true fiord. The walls of Sandy beaches occur along the long sweeping beaches broken by the bays are usually steep, and sides and heads of inlets and bays wide-mouthed rivers and resem many headlands are characterized but are less well developed than bles a ria coast (Lobeck, 1939). by cliffs. Beaches are generally along the eastern shoreline of The shoreline features were poorly developed and are com- Prince William Sound. EFFECTS ON SHORE PROCJ Contrasting sharply with the ir ingly contradictory evidence of displacements and the long-term regular shorelines of Kodiak Is both uplift and subsidence-a con trend of Holocene coastal emer land and Prince William Sound is tradiction that perhaps is not sur gence or submergence, as well as a the more uniform one of Cook In prising when viewed in the light remarkable widespread submer let. Cook Inlet extends into the of the complex tectonic history of gence during the past several cen mainland more than 175 miles and the region. The high Chugach turies over much of the zone that narrows and shallows towards its Mountains, Saint Elias Mountains, was uplifted during the earth head. The backshore, particularly and Fairweather Range are ob quake, and at least part of the zone east and north of the inlet, con vious manifestations of strong tec that subsided (Plafker and Rubin, sists of low gently rolling glacial tonic uplift. Raised beaches along 1967; Plafker, 1968, in press). outwash plains. Wave-cut bluffs as some coasts indicate more recent Thus, according to Plafker, the high as several hundred feet occur uplift, also, but the drowned fiord tectonic movements that accompa in that area, and the adjacent like character of much of the shore nied the earthquake were but one beaches are generally well devel line, combined with numerous off pulse in a long-continuing trend oped. At the head of Cook Inlet shore islands, skerries, and reefs, of diastrophic deformation that the waters are shallow, and broad suggest coastal subsidence and has resulted in regional emergence silty tidal flats are common. South submergence. of parts of the continental margin, of Tuxedni Bay, on the west shore Reconnaissance studies of the simultaneous submergence of the of Cook Inlet, the low coastal plain Kenai-Kodiak Mountains belt, and pinches out, and mountains rise displaced shorelines, paced by nu either relative stability or emer abruptly from the sea. merous radiocarbon dates, have Much of the shoreline affected brought out a genera·} similarity gence along the shores of Cook In by the earthquake presents seem- between the pattern of earthquake let and pa.rts of Shelikof Strait. COASTAL FEATURES AND EARTHQUAKE EFFECTS FEET BEACHES Frontal ridge The beach face is the area be or berm High water w c. ·:L tween high and low water (fig. 2) . 0 0 30 FEET It is an ever-changing feature, but Vi normally the changes are subtle and become noticeable only during severe storms. During the earthquake of 1964, 1------Beach face ------1 rapid changes in land elevation 2.-Diagram illustrating beach features. caused obvious changes in shore processes and beach-face morphol ogy. These changes were compara CHANGES IN PROFILE AND ent from 1 : 8 to 1 : 30 and are ble in magnitude to changes that GRADIENT characterized by a break-in-slope 50-200 feet seaward of the high normally are caused by centuries Obvious changes in profile and water 1ine. The break-in-slope long fluctuations in sea level-or, gradient occurred along shingle paradoxically, to sudden changes marks the location where waves act beaches within the submergent longest at high tide (King, 1959). caused by severe storms. Thus, areas. In those areas, changes were changes in the beach face follow The beach face (fig. 2) shoreward noticed within 1 week after the ing the earthquake are important of the break (termed the "upper earthquake. The most noticeable both to the study of fluctuating beach face") has a steeper gradi sea level as it affects a beach and to change was a flattening of the ent and coarse·r material than does the engineering problems that gradient and a recession of the the lower beach face. The break might be met along the beach face beach face. in-slope shown in figure 3 is typical as a result of changes caused by Many shingle beaches within the of those on many shingle beaches storms. submergent area.s range in gradi- in Alaska. 298-580 0-68~2 J4 ALASKA EARTHQUAKE, MARCH 27, 1964 concluded in part that a raised sea level is followed by shoreward dis placement of the beach profile as the upper beach is eroded and that the amount of material eroded from the upper beach is equal in volume to that deposited on the nearshore bottom. Thus the rise of the nearshore bottom tJhat results from this deposition will ulti mately equal the original rise in relative sea level. Along beaches protected from severe storm waves, adjustment to subsidence differed somewhat from that on exposed shingle beaches such as Homer Spit. Within the protected areas, for example those along the south side of Kachemak 3.-Sharp break-in-slope between upper and lower beach faces extends from mid Bay and certain shores of Kodiak foreground to midcenter of photograph, just to right of man. These features, here seen Island, recession of the beach face in Kachemak Bay at low tide, are common to many shingle beaches. was more uniform and the convex upward profiles were less notice After earthquake-caused sub active erosion along the break-in able because wave action was less sidence, waves reached higher on slope and the development of a new turbulent. Erosion along the new the beach face •and caused severe postearthquake frontal ridge. Dur break-in-slope and swash action scour erosion of the upper face; ing this stage the beach became along the beach crest were also less the break-in-slope gradually noticeably convex upward because severe. Thus, the rate of beach-face shifted shoreward. The upper material from near the break-in recession along the beaches not limit of the swash was also ex slope moved toward tJhe upper acted on by large waves was more tended at some places, and the beach face. The third stage was uniform and less rapid than along frontal ridge, or berm, was over characterized by development of a exposed beaches. flowed. Part of the material eroded well-defined break-in-slope tJhat Even less noticeable changes oc from the beach :Jiace was thus car had gradually shifted landward. curred along sandy be-aches, prob ried by the swash over the frontal Erosion and recession of the beach ably becam;e their gradient is usu ridge and was deposited along the face continued until the slope ap ally flatter than thrut of shingle land ward side. proached the preearthquake gra beaches and because sand is less A good example of profile and dient. During the third stage the readily moved by wave action than gradient changes •along a shingle new frontal ridge increased no is shingle. beach within the submergent areas ticeably in height •and eventua'lly One area of subsidence where was afforded by beaches along retarded overflow. During this sandy silty beaches predominate is Homer Spit. Adjustment of the stage also, some of the material upper Cook Inlet. That region is Homer Spit beaches to the new carried by the longshore drift be characterized by an estuarine en gan to accumulate along the lower high-water level was gradual but vironment where the beach mate can be described as occurring in beach face near the break-in-slope. rial consists largely of silt-sized three stages (fig. 4). The first stage The observed erosional ·and deposi particles derived from glacier-fed was characterized by severe ero tional effects of a relatively raised sion and planing off of the sea level on tJhe Homer Spit streams (Karlstrom, 1964). Storm beach face and crest by wave and beaches are in agreement with sug waves seldom exceed 4 feet in swash overwash. Part of the eroded gestions made originally by Bruun height. The beach gradient is as material was carried across the (1962) and partly tested by low as 1 :500 and, because the beach beach crest and onto the spit. The Schwartz (1965) with small-scale is acted upon by a tidal range of second stage was characterized by l-aboratory experiments. Bruun 35 feet, silty mud flats several EFFECTS ON SHORE PROCESSES AND BEACH MORPHOLOGY J5 MINOR BEACH FEATURES lst stage Minor beach forms including cusps, small beach ridges, and steps began to reappear on all submer / / Preearthquake HWL // Planing-off of gent beaches within a few weeks ------;11" face and crest // after the earthquake. The new / / beach cusps were generally poorly developed and irregularly spaced upon the beach. Some of the hol lows were overly large-being 30- 40 feet wide as compared with pre earthquake forms 5-15 feet wide. 2d stage Frontal ridge The outlines of the forms were Yague, and at some places one horn Face convex upward was two to three times longer than the other. In all known examples, however, when the beach face itself Erosion along break in slope began to revert to the preearth quake form, the cusps also began to develop gradually into pre earthquake forms. 3d stage On beaches where the gradient was lowered by initial postearth Postearthquake HWL quake processes, cusps did not re / // EXPLANATION appear until the gradient had / / / steepened, possibly because lack of / / Dashed line represents preearthquake / mobility of the materials retarded / frontal ridge the formation of the beach cusps. Solid line represents beach profile On beaches where the gradient was at various postearthquake stages initially steepened after the ea.rth HWL High water line quake, poor I y defined cusps formed early, that is, within 3 4.-Sketch of three stages that characterized the postearthquake changes of beach months after submergence. These configuration in the submergent areas. Sketch is based on behavior of the beach on cusps were alternately destroyed the Cook Inlet side of Homer Spit, but applies to many other beaches. and rebuilt by large storm waves, however-a process that suggests miles wide are exposed during low action of a storm is usually meas that beach cusps will not form, or water. Subsidence of the region ured in hours. at least will not persist, if the was not uniform but was as much "\Vithin the emergent areas, as gradient of the beach flattens be as 2 feet. Some beaches examined along the Copper River Delta, the low a critical gradient. Along shortly after the quake showed no profile and gradient of the up Homer Spit, this gradient appar noticeable change in profile or lifted beaches remain unaffected ently is about 1 :20 for shingle gradient, but by mid-1967, 3 years with respect to wave action. The beaches. after the earthquake, subtle changes that have taken place are Prior to the earthquake, small changes in profile had occurred. related to abandonment and beach ridges and steps occurred The action of shore processes stranding of the former beach along the upper beach face of most following subsidence of the coastal faces above high water, and to ex shingle beaches. Submergence de region and the resultant effects on posure to the normal processes of stroyed or greatly altered both the beaches were similar to the subaerial erosion. In time, of features. However, the ridges and effects of a severe storm. However course, new beaches will develop steps began to develop in approxi the changes resulting from subsi below the abandoned ones to fit mately the same location on the dence must be measured in years, the postearthquake high-water postearthquake beach face about 3 whereas the maximum destructive lines. months after subsidence. Unlike J6 ALASKA EARTHQUAKE, MARCH 27, 1964 beach cusps, the ridges and steps occurred in the runnels within a tion on the landward side, such as became stabl.e within 1 year after few weeks after the earthquake, that by which a new frontal ridge submergence. and at numerous places exposed a forms along the crest of a beach. much coarser bed material. During Instead, the process seems to be LOW-WATER FEATURES the same period the ridges became one of flattening and spreading of rounded and more symmetrical in the material followed by a land The most prominent low-~water features on beaches are ridges, run profile. The heights of many ridges ward movement of material en nels, and submarine sandbars. AU increased ·a foot or more. At many masse. As the landward migration three forms 'vere modified by the places where the preearthquake of sand is slowed by its deposition earthquake, and the changes ob ridges were hard enough to sup at a higher elevation on the beach, served give some insight into the port the weight of a man without runnels begin to form. '\Vater movement of material and the de appreciable indentation, the post draining from the beach contrib Yelopment of such :forms. subsidence ridges were soft. Ap utes to the process by eroding sand proximately 30 days after the from the channels. The eroded RIDGE AND RUNNEL earthquake, many of the ridges sand is thereafter transported to had widened, some to as much as the lower beach face where part Ridges and runnels occur along several hundred :feet, from previ of it is eventually carried down most beaches of low gradient ous widths of a few scores of feet. beach by littoral currents. For this where sand is available and where During the 'videning process the reason there was a persistent me the tide range is large enough to adjacent runnels were partly filled, andering and relocation of the expose several hundred feet of and low basins were left in some runnel courses during the first beach face at low water. Good ex areas to serve as drainage chan year following subsidence, some amples are found a]ong many nels. Ridges and runnels that were thing that had not been observed beaches of Al This relocation is suggested by ridges along the Alaska coast are RESPONSE TO SUBSIDENCE AND UPLIFT previously reported hard bottoms composed of shingle, often with in anchorages that, after the earth minor amounts of sand. A beach Changes in beach ridges occurred quake, were composed of soft sand. ridge along the present shoreline is in many submergent areas. The This condition was particularly generally referred to as a modern magnitude of the changes depend noticeable along Homer Spit or frontal ridge, whereas the ed on (1) the extent to which the where scuba diving showed that ridges farther inshore are referred land was submerged, (2) the geo preearthquake areas of hard to as ancient or old ridges. gra phie lo'cation of the beach with packed sand were characterized by Most individual ridges are 5-6 respect to storm waves, ( 3) the soft loose sand within a year after feet above high water and 8-10 slope of the beach face, and ( 4) the the earthquake. feet wide, but some are as high as type of beach material. In shel In some areas, particularly in 20 feet and their bases may be as tered areas where submergence was Prince William Sound, submarine wide as 200 feet. Most ridges even only about 1-2 feet., changes were sand bars apparently were altered tually become stabilized by vege minor, but in areas of greater sub or destroyed by seismic sea waves tation that establishes itself on the sidence and exposed sea conditions or by local waves. G D. Hanna land\vard slope. the changes were often major. (written commun., 1965) states Frontal ridges grow gradually In Borne areas, such as along that soft sediments were scoured in both height and width by the Homer Spit, subsidence caused from many shallow bottom areas. deposition of m&terial carried onto waves to reach as much as 6 feet Elsewhere submarine bars were al and across the ridge crest by waves higher on the be1ach face than be tered even though tsunami effects and s'vashes during storms. As the fore the earthquake, and s·washes were not evident along the shore ridges increase in height, the abil overflowed the crest of the frontal line. ity of the overwash to carry debris ridge. Material along the upper across them decreases. Thereafter beach face, which was formerly MODERN BEACH RIDGES material will accumulate along the above all but the highest waves Beach ridges (also referred to as sea m for buildup of material, and land ward migration of the beach ridge may continue indefinitely. This condition is exempli'fied by the barrier beach at Breving Lagoon, on the Sewa.rd Peninsula, :far from the area where shorelines were af fected by the earthquake (fig. 6). This barrier beach has a maximum width of 500 feet and is separated from the mainland by a shallow lagoon as much as a mile across. The beach is migrating landward, rupparently because of storm-wave ruction and the resultant process of overflow. Material eroded by storm waves from the seaward side and transferred by overflow to the landward side of the barrier beach 5.-0verflow of the crests of some beaches caused material to be carried and spread is carried into, and spread out on out along the backshore, left half of picture. Gradually the material accumulated into the floor of, the lagoon. Because a new and higher frontal ridge. View along Homer Spit, looking southeast. the lagoon affords no pla.tfol'ln on which overflow material can ac was deposited near the crest and material was deposited along the cumulate there can be no apprecia the finer material was carried to crest than 'along the landward side; ble widening of the barrier beach, ward the backslrore. Along the the height of the ridges thus gra:d and therefore, the height of the crest and the seaward side of the ually increased. ·when the ridges beach cannot be increased. Hence ridge, the material \YaS poorly had increased sufficiently in height under normal storm conditions the sorted because of the severe scour. to prevent overflow, migration beach will continue to migrate On the landwa,rcl slope of the fron stopped and the ri'dges stabilized. land\\"ard; the landward migration tal ridges, the sorting was gen Observations of the migration is not dependent on a rise in sea erally better and the grain of beach ridges after the earth level. size decreased. Aloi1g the extreme quake suggest an explanation as Unlike the large ridges along landward edge of the frontal to why some ridges appear to shingle beaches at such places as ridge, the overflow material was migrate even under conditions not Homer Spit, beach ridges along delicately layered in :fanlike forms necessarily related to a rise in sea sandy beaches on the east shore of and consisted of silt, &'tnd, and pea level. As stated above, beach ridges Cook Inlet were destroyed in many sized gravel. along Homer Spit migrated land areas, particularly along the toes Continued overflow and the \Yard under conditions of re}a of ]my bluffs. In such areas the transfer of material from one side ti,rely higher sea level, N1e migra widths of beaches between t lw of the frontal ridges to the other tion being brought about by the high-water line and the bluff toes caused the ridges to migrate to process of overflo,Y. Migration of pr-ior to the earthquake ranged ward the hackshore. The transfer the ridges ceased, however, when from 25 to 150 feet. . \ fter sub of material from one location to the width of the ridge was suffi sidence the beach widths \H're de t:he other led to a net loss along cient to :furthet' the heightening by creased and the small beach the seaward side and a net gain deposition of material along the ridges-those from 1 to ± feet along the hndward side. Thus the crest. It is concluded, therefore, high-were destroyed. The rela process of land'"'ard ridge migra that a beach ridge will stabilize if tively narro\Y width of such tion was accomplished by the there is sufficient backshore area beaches prevented overflow ma transfer of material within tJhe upon which the overflmy material terial from accumulating, and ridge proper. ca.n accumulate. thus the beach ridges could notre During overflow of the frontal If a barrier bE)ach fronts a treat landward when acted on by ridges a greater volume of coarse lagoon, then there is no platform tt sea }eye] as much as 2 feet higher EFFECTS ON SHORE PROCESSES AND BEACH MORPHOLOGY J9 6.-Part of the barrier beach at Breving Lagoon, Sewtard Peninsula. Lagoon is north of (above) bE'ach; Bering Sea is south of lhelow) beach. The lagoonward migration of the barrier beach is shown by superposition of the overflow upon the cuspate spit. i\Iost beaches in the earthquake-affected part of Alaska migrated landward only short flistances because they were backed by land platforms that allowed overwash material to accumnlatP. Photograph IJy Ala~ka Highway Department. (fig. 7). Thus, the material, in 7.- SubmergE'nce caused the high-water line to shift to a higher elevation on this stead of accumulating higher on beach on the eastern shore of Cook Inlet. The establishment of a new high-water the beach (as it did along Homer line caused undercutting and sloughing of bluffs. Note absence of beach ridges. Spit) was dissipated by waYe action and was transported a way from the site by the longshore drift. As the bluffs in such areas erode and recede, the beaches will eventually regain their preearth quake "·idths, and new beach ridges similar to those that existed before the earthquake should develop. In the uplifted areas the old frontal ridges are abandoned and stranded above high "·atel'. Ne"· ridges haYe formed in some places, and rather rapidly. In most areas, however, the growth of nmv ridges has been slow, probably because the predominantly fine material JlO ALASKA EARTHQUAKE, MARCH 27, 1964 along the preearthquake lower by seismic shaking may also con height from compaction and set beach face does not form stable tribute to a change of coastal tlement, therefore, probably would bea:ch ridges as readily as does forms. The 1964 earthquake caused occur between the modern frontal shingle. The old ridges in the up compaction and settlement of sedi ridge and the mainland and would lifted areas will gradually be ments in many parts of south-cen lead to the typical basinlike profile covered by ve'getation and ~will tral Alaska (Kachadoorian, 1965; that characterizes so many coastal then assume the character of the Coulter and Migliaccio, 1966; Wal const.ructiona.l forms along the typical old beach ridges of many ler, 1966a). Coastal forms must south-central coast of Alaska. coastal areas. N e>v ridges along the have been subjected to similar com lower high-water line will begin to paction processes many times : STREAM-MOUTH CHANGES develop as material continues to During the past 50 years that offi Stream mouths were changed be worked by waves. However, the cial records have been kept, hun throughout the areas of uplift and new ridges probably will require dreds of earthquakes have occurred subsidence. In uplifted areas, several years to stabilize, mainly along the Alaska coast (U.S. Coast streams were lengthened and in because of a lack of coarse source and Geodetic Survey, 1964, p. 23). cised into the elevated beach face. material. As new beach ridges develop, In the submergent areas, streams the coastal form widens seaward were shortened and drowned. ANCIENT BEACH RIDGES with a corresponding increase in Postearthquake studies of sub thickness of the column of sedi SUBME.RGENT A.RE:AS ment. The coarsest material is usu sided coastal forms afford an ex Stream mouths were drowned planation for the fact that the ally near the mainland and the smaller particles along the seaward throughout the submergent areas. crests of some ancient beach ridges Maximum drowning occurred are uniformly lower than the mod side. If the mass of this sediment is repeatedly subjected to seismic mostly at the mouths of low-gra ern or frontal ridge. In some areas dient streams that flowed across this condition is sufficiently pro and microseismic shocks, the sedi ments-particularly the finer par low-flying backshores composed of nounced to result in a basin-shaped water-laid sediments. Within such area between the frontal ridge and ticles-will lose bearing capacity and settlement will follow (Ter areas, subsidence is attributed both the mainland. This habit of Alaska to tectonic movement and compac beach ridges has also been noted zaghi and Peck, 1948). In some kinds of sediments, vibration can tion of the sediments ( Kachadoori else>vhere (Bird, 1964; ,Johnson, an and Plafker, 1967, p. F27; Ka 1919). lead to spontaneous liquefaction which would cause additional set chadoorian, 1965, p. B2), and the ,Johnson (1919), Fisher (1955), extent of stream drowning is a and Zenkovitch (1959) at.tribute tlement. Even though the coastal form function of both. the relatively lower crest elevation nearest the mainland is oldest and The most notable examples of of the older ridges to a continuous hence has been subjected longest stream-mouth drowning are along rise in sea level whereby each suc to seismic action, the sediment lay the shores of Kodiak Island and cessive frontal ridge builds higher. er there is thinnest and the size of the southern Kenai Peninsula This is well illustra.ted along the particles is coarsest. Compac where subsidence of the land 'vas Homer Spit; as a result of the tion by seismic shaking, therefore, 5 feet or more in some locations earthquake-caused rise in relative would be less in such areas than (Alaska Dept. Fish and Game, sea level, the frontal ridge here has in the seaward pa.rt of the land 1965). Several excellent photo been built higher than the older form where the sediment is thicker graphs of drowned streams on ridges. If a rise in sea level is the and the particle size is smaller. Kodiak Island are shown in a re only factor at 'vork, hmvever, the Although the modern frontal port on that area by Pia fker and profile between the frontal ridge ridge has been subjected to fewer Kachadoorian (1966). and mainland should have a gentle earthquakes than have the ancient During the earthquake many landward slope rather than the ridges, sediment compaction does bays along Kodiak Island were commonly observed basin-shaped occur there also. However, any de hit by seismic sea waves. Spits, profile. crease in height caused by compac bay-month bars, and barrier Studies by the author after the tion would perhaps be offset by the beaches at or near stream mouths earthquake suggest that com pac addition of new material brought were altered or dest,royed. Some of tion and settlement of sediments in by waves. Maximum decrease in the lovver of these landforms were EFFECTS ON SHORE PROCESSES AND BEACH MORPHOLOGY JU overwashecl, eroded, and reduced in height. New outlets formed where the tsunamis tore channels through ridges and spits. In all examples known to the writer, stream mouths that were acted upon by tsunamis "·ere "·idened by scour and erosion. Since the earthquake, erosion by normal "'ave and S\Yash overflow has gradually caused many coastal features such as spits and barrier beaches to flatten in profile and recede hmdward. Thus, the effect of the tsunami and of normal wave action has reduced many once-con spicuous forms to flattened, poorly defined deltaliko features. In some areas of active shore drifting, material eroded by ''"avo action 8.-Tectonic uplift created new lands permanently above high water, such as this from the stream mouths has re area along the Copper River Delta. View at high tide, several months after the earth plenished the beach along the quake. The preearthquake high-wat('r line is shown approximately by the dashed line. downdrift side. In areas of w&'tk Photograph by U.S. Forest Service. or inactive shore drifting the eroded material is merely spread out on the lower beach face. by the decreased supply of mate from the mouths and carried with In certain streams of lo''" gradi ria,l is not yet clear; ho\Yever, be other debris into the upper reaches ent and velocity, the shores ''"ere cause of a decrease in stream-borne of the streams. Such deposition subjected to strong mtve action material, because wider stream caused considerable silting in when the land subsided, and mate mouths ''"ill retard longshore stream mouths and channels, and rial eroded from the u nconsol i drifting and by-passing of mate in some streams caused a tempo dated deposits aJong their banks, rial, and because of continuing rary damming or blocking. Spits such as deltas and ouhYash fans, ''"ave action, beach erosion prob a,nd barrier ridges at stream was transported by waves into the :tbly will characterize many mouths were generally altered by stream mouths. This process is par dro,Yned stream-mouth areas for the tsunamis. Many of the lower ticularly noticeable along Turn many years to come. beach forms were appreciably again Arm in upper Cook Inlet, changed, and material was redis where mud is accumulating in UPLIFTED AREAS tributed along the beach into the dro,Yned stream mouths. stream mouth. Such redistribution In some areas the drowning of Changes at the mouths of streams in the uplifted areas are of the material even obliterated streams has decreased the supply some stream courses. of material for natural beach related to stream-course lengthen Along appreciably uplifted nourishment. By reducing stream ing and dO\mcutting (fig. 8). shorelines composed of sand and gradients, submergence has led to These changes range from minor silt, rapid gullying occurred at prograding rather than degrading alterations along shorelines of stream mouths (fig. 9). Along the of channels. Stre:Lm erosion there little npli ft. to major changes along Copper River Delta, an area of fore is Jess effective than it \YRS gently sloping, easily eroded readily eroded sand and silt that before the earthquake, and the re beaches in areas that \Yere appre was uplifted several feet, gullying duced quantity of debris carried ciably uplifted. commenced within hours after up by the strea,ms diminishes the The effects of tsunamis on lift (Reimnitz and Marshall, qua,ntity of materia,l availa,ble to stream mouths in the uplifted 1965). Rapid head\Yard erosion the longshore ch·ift. The extent to areas varied widely. In many produced small waterfalls 1-2 feet "·hich the beaches ''"ill be affected pla.ces, sand and silt were scoured high. J12 ALASKA EARTHQUAKE, MARCH 27, 1964 wave erosion, none were affected more than the east shore of Cook Inlet from Kachemak Bay to Turnagain Arm-a distance of more than 170miles (fig.1). There the entire shoreline is eroding. As already mentioned, the shoreline is a relatively uniform sandy beach with slopes as low as 1 : 300. The tidal range is about 22 feet along the southern section but increases to more than 30 feet near Turn again Arm. Because of the low beach gradient and high tidal range, several thousand feet of tidelands are exposed at low water. The beach is backed by a line of bluffs about 200 feet high in most places, but locally as high as 600 9.-Rapid gullying and sloughing caused by headward stream erosion along the feet in the Homer area. Most of uplifted coast on the Copper River Delta. Photograph by U.S. Forest Service. the bluffs are of unsorted glacial material that is easily eroded. Prior to the earthquake, wave Along beaches of mixed sand overall result was an increase in action was undercutting the bluffs and shingle, stream adjustments material carried by the streams in many areas. Most of the sandy were slower. Small riffles formed and deposited at their mouths. fra;ction of the sloughed material at stream mouths along su~h Along some stream mouths the drifted away, but part of the beaches. newly deposited material has re coarser mat~rial remained along Kirkby and Kirkby (1968) de tarded channel development and the high-water line in the form of scribed in detail stream-mouth rud has led to meandering. Along the shingle on beach ridges. The j ustment along elevated intertidal larger streams the process has been ridges, which were as high as 8 zones composed of sand and shin mainly silting and dissection of feet, protected the toes of the bluffs gle at Montague Island, where up newly formed deltas and spits. from all but the larger storm lift was as much as 33 feet. As on Although evidence indicates an waves. the Copper River Delta, stream ad increase in sediment carried by the During the earthquake the justment began immediately after streams, the length of time the shoreline subsided as much as 3% uplift had occuvred. increased load was carried prob feet along the southem section Along some elevated shingle ably was short. By the fall of 1964, near Homer and as much as 1 foot beaches, streams disappeared into 6 months after the earthquake, the near Point Possession at the mouth the gravel of the uplifted inter stream-carried sediment load was of Turnagain Arm. Prior to sub tidal zone. Generally this condition normal (Waller, 1966b). mergerice the width of beach be was temporary, and after several tween the high-"·ater line and the months the streams developed new COASTAL EROSION AND MOVEMENT OF MATERIAL toe of the bluff was generally less courses across the intertidal zone. than 100 feet, and in some areas Most uplifted stream courses EROSION less than 20 feet. Submergence de showed evidence of degradation creased these widths and, after the and bank erosion within a few days Coastal erosion is active along after the earthquake. Slumping of all shorelines within the area af earthquake, storm waves, pal'ticu bank material and debris deposited fected by the earthquake except on larly along the southern section, by seismic sea waves also contrib the rocky platforms. The shore acted directly upon the toes of the uted material. In addition, after lines most affected are those com bluffs. Many beach ridges that had spring breakup, the normal in posed of unconsolidated material previously protected the toes of the crease of streamflow made deposi within the submergent areas. bluffs were exposed to ''"aves of tion of material all the greater. The Of the shorelines modified by e\·en, moderate height (fig. 10). EFFECTS ON SHORE PROCESSES AND BEACH MORPHOLOGY J13 The two communities along this shoreline most seriously affected by bluff erosion were Kenai and Homer. Kenai is at the mouth of the Kenai River, a tidal estuary. During the earthquake the area subsided 12-18 inches. South of the town, bluffs as much as 150 feet high consist of readily eroded glacial material and alluvium. After regional subsidence, the preearthquake accumulation of sloughed debris along the toe of the bluffs was quickly removed. Undercutting by waves and by the river began a few days after the. earthquake, and within 3 months the bluffs had receded as much as 20 feet (fig. 11) . 10.-Undercutting and sloughing of bluffs caused by tectonic subsidence, eastern In the Homer area the regional ;;bore of Cook Inlet. Driftwood along toe of l.Jluff indicates the position of post· subsidence was about 31/z feet. Par earthquake high-water line. ticularly damaging wave erosion occurred in the. Millers Landing area, toward the east end of Homer on Kachemak Bay, along a low line of bluffs composed of peat, sand, and silt. After the earth quake, undercutting caused seri ous sloughing; within 6 months, the bluff line had receded as mnch as 8 feet. SHORE PROTECTION MEASURES Except at Homer and a few small villages, no serious effort has been made to construct erosion preventive works any\Yhere in the earthquake-affeeted area. Along the Cook Inlet side of Homer Spit, erosion on the lee side of the. groin farthest down drift became critical. Retreat of the beach was jeopard izing the spit higlmay. In July 1964, a seawall and two additional 11.- Serious bluff erosion caused by subsidence along the waterfront of the town of groins "·ere. constructed. Two hun Kenai. View looking northwestward, about 30 days after the earthquake. dred feet of the. \Yall was con structed to a height of 1-2 feet above the high-water line, and one By 1967, 3 years after the e.arth mediate-size storm \Yaves still section was built 5 feet higher qua.ke, the. bluff line. in some areas ( 1 967) erode the toes of the bluffs. above the high-water line. Figure had receded sufficiently to provide l -ntil the bluff line recedes enough 12 shows the. timber bulkhead and a width of beach that afforded pro to provide a sufficient bea:ch to pre the additional groins a short time tection from all but the ln.rger vent \ntve nmup to the toe, erosion after construction. Figures 13 and storm waves. Elsmd1ere inter- and recession "·ill continue. 14 show the same area 6 and 16 J14 ALASKA EARTHQUAKE, MARCH 27, 1964 12.-Timber seawall and new groms along west side of Homer Spit as constructed 3¥.! months after earthquake-caused subsidence. 13.-Seawall shown in figure 12, approximately 6 months after construction. EFFECTS ON SHORE PROCESSES AND BEACH MORPHOLOGY J15 anchored in unstable beach gravel. Elsewhere wire-mesh baskets filled with cobbles were placed along the beach to serve as bulk heads. Such baskets appeared to function well along Homer Spit, even though they were pounded by waves as high as 10 feet. Erosion, moveover, occurred on neither the updrift nor the downdrift side. A similar cobble-filled "·ire-mesh fence was started at Larsen Bay on Kodiak Island (fig. 15), but most of it was destroyed by storm waves before it could be com pleted. Wave erosion of landslides caused by the earthquake was rapid, particularly along Cook In let where the frontal edges of the 14.-Seawall shown in figure 12 some 16 months after construction. Note that the bulkhead and one of the groins were completely destroyed during this period owing to slides were greatly modified within their exc!'ssive height. 2 years. Many slides consisted of sandy-silty material. Silty-mud beaches have developed gradually, particularly on the downdrift sides. Erosion within the uplifted areas is evident along the post earthquake lower high-water line. Wave erosion along most of the uplifted area is not serious so far as loss of land is concerned; most streams across elevated tidal flats are incising channels. LONGSHORE MATERIAL MOVEMENT No significant changes resulting from the earthquake are known or reported for the directional habit of tJhe longshore drift. The changes that have occurred are only in the quantity of material carried. 15.-Cobble-filled wire-mesh fence under construction at Larsen Bay, Kodiak Island, Along most shorelines aJfected by shortly after the earthquake and resultant subsidence of 2 feet. Most of the fence the earthquake, more material has was destroyed by a storm before it could be completed. entered the longshore drift than before. T'he additional material began months later, respectively. Sixteen constructed in other areas but months ,after construction, the most were destroyed within several to enter the sea immediately a.fter high timber bulkhead between the months, or at most within a year, the earthquake. This fact was fifth and sixth groin had been de after the earthquake. Failure is made obvious a.long many shore stroyed, as had the last groin (fig. attributed to the fact that the lines by a broad band of muddy 14). Similar high bulkheads were bulkheads were too high and were water that was several miles wide J16 ALASKA EARTHQUAKE, MARCH 27, 1964 NE sw A '------""' ""' ""' "'------...... _ __ ------B ------_____ ...... ------...... __, ~ ------ c EXPLANATION Groin Downdrift, southeast side Updrift, northwest side 33 52 67 80 96 125 150 166 184 196 216 MEASUREMENT POINTS 16.-Profiles of updrift and downdrift fill of groin at Homer Spit, measured (A) on March 2, 1964, a few weeks prior to the earthquake; (B) on August 2S, 1964, 4 months after submergence; and (G) on September 30, 1965, 18 months after submer gence. The change in configuration of the groin fill was caused by submergence and the resultant higher level of water on the filL Note, however, that the gradient at 18 months approximates the preearthquake gradient. EFFECTS ON SHORE PROCESSES AND BEACH MORPHOLOGY J17 in some areas, but no direct effect, quake (Stanley, in Waller, 1966a.). ends of the groins (fig. 16B), but such as the formation of new Significant changes in material about 30 days after the earthquake berms by the deposition of the ma movement ma.y therefore lmve the intergroin fills began to en terial, was observed along beaches passed unnoticed. large, and thereafter the enlarge until several weeks a.fter the earth The study was made by the ment increased noticeably. The quake. A good example of the effect Alaska Division of Lands along material causing the increase prob of a delayed longshore drift is de the west side of Homer Spit at a ably was brought there by the scribed by Stanley (in Waller, system of filled groins that had longshore drift. 1966a, p. D24). At Homer Spit been studied prior to the earth Observations indicate that dur the additional quantity of material quake. ~\fter submergence the ing the 30-day period following that had entered the longshore high-water line rose 3.5 feet. \Vith the earthquake, the material de drift in the source area, 2-6 miles in 5 days after submergence, 1-2 posited along the beach crest came west of the spit, did not reach the feet of material had accumulated from the lower-upper beach face spit until about 30 days after the along the land"·ard end of the of the groin tills and was carried earthquake. groins and had spread inland to a upslope. Erosion along the lower Aecelerated shoreline erosion in width of ;)0-50 feet. The newly de upper beach face continued until a the snhmergent areas caused more posi,ted material was first thought new profie of equilibrium had been material to enter the drift than to ha ,.e been carried in by the long established. The dominant move had been entering before the earth shore drift. However, the first pro ment of material during the 30- quake. However, in the same areas, files made 7 days after submer day period following subsidence material contributed by rivers and gence indicated that the intergroin was upslope because the waves streams decreased. The converse fills had actually receded and \vere reaching higher up the beach was true in the uplifted areas. flattened and all had undergone a face. \V aves running higher up \:Vhat effect the change in balance net loss of material (fig. 16A). In the beach face shorten the travel of the source and supply of mate asmuch as the material lost from distance of the swash and thus in rial 'ivill have on the character of the intergroin till area about crease its carrying capacity. the longshore drift is not yet equaled the newly deposited ma The increased shoreline erosion known. In planning future coastal terial along the landward end of throughout the area unquestion projects the possible changes in the groins, the material probably ably increased the supply of ma was deri \·ed from the adjacent in source tmd supply that have oc terial to the longshore drift; after tertill area rather than from some curred since the earthquake must about BO days a noticeably in distant source. be taken into consideration. Additional profiles were made creased quantity of material was drifting alongshore, but during UPSLOPE MATERIAL MOVEMENT at about 15-day intervals for the next 60 days (fig. 16B, 0). Within this first :30-day period following Only one limited study of ma the first BO days the intergroin fills submergence the dominant motion terial movement was made 'vithin receded as material continued to of material was up the beach the first year following the earth- accumulate along the landward rather than 'along it. BIOLOGIC EFFECTS OF SHORELINE CHANGES damage to this resource has not yet Kodiak Island, important inter been made, the environment and tidal spawmng grounds were FISH habitat of the salmon is known to inundated. At the time this report was have been drastically changed in G. Y. Harry, Jr. (written com written (1967), the most compre some areas. nnm., 1964), reported, 5 months hensive discussion of the effects of Part of Prince ·william Sound after the earthquake, that the the earthquake on the Alaska fish "·as uplifted as much as 33 feet, greatest damage to the salmon in eries ''"as the one compiled by the and great changes in the environ Alaska was probably in Prince ~\laska Department of Fish and ment and habitat of pink and 'Villiam Sound; here 75 percent Game ( 1965) . Although a, com chum salmon resulted. Similarly, of the pink and chum salmon pro plete analysis and assessment of in the submergent areas, such as duction comes from the intertidal J18 ALASKA EARTHQUAKE, MARCH 27, 1964 spawning areas. Thorsteinson the preearthquake lower areas are WILDFOWL (1964) states that within Prince now characterized by excessive Ordinarily submergence or William Sound the runs of pink quantities of sediments that de emergence v.ould not be considered salmon range from 3.2 to 8.7 mil crease the survival rate of salmon to affect \vaterfowl adverse,ly, but, lion fish and the chum salmon eggs and alevins. according to P. E. K. Shepherd from 0.4 to 0.6 million fish. (written commun., 1966), there Compounding the pe,rmanent SHELLFISH has been an indirect e,ffect. In the damage caused by uplift and sub One of the more important feeding ground of the dusky Can mergence of the intertidal spa,wn habitats of shellfish, particularly ada goose in the Copper River ing grounds was the temporary the razor clam, is along the Copper Delta, the preferred food of the effect of tsunamis and local waves. River Delta. The delta was up goose is a type of vegetation refer In parts of Prince William Sound, lifted as much as 8 feet, and, be red to as "forb-grass." This the waves caused considerable cause of the low offshore gradient, grass-actually a combination of scour, and debris and silt were car extensive intertidal areas \vere herbs and grasses-apparently re ried upstream for seveml hundred permanently elevated above high quires occasional inundation by feet. Some biologists believe that water. This area supported a large marine waters and usually grows many sa,lmon eggs were scattered population of razor clams. The along the sides of tidal sloughs and by the movement of debris. When, widespread death of these and other areas regularly inundated by all contributing factors in Prince other bivalves throughout Prince the highest tides. Because of William Sound are taken into ac William Sound was evident changed tide levels, the forb-grass count, the salmon loss caused by within a few \veeks after the earth is dying, and before it is reestab the earthquake and its subsidiary quake (G. B. Haven, written lished at a higher elevation, the effects is thought to be about one commun., 1965). Many of the clam quarter of a million salmon dusky Canada goose is likely to beds are nmv above high water and ( N oerenberg ~1nd Ossiander, have changed its habitat. Shep 1964). are lost, but clam beds formerly herd indicates that the habitat of In the Kodiak Island area, below lower low water were the goose may be further changed where submergence was as much elevated and are now accessible to because its former nesting grounds as 6 feet, widespread flooding of clam diggers. In some areas of 'vill become overgrown with coni the intertidal spawning areas oc Prince ·william Sound, particu fers or other plants \Yhen the salt curred. In some places flooding of larly aJong the western part, sub is leached out of the soil. To some the intertidal area was helpful to sidence at the bay heads was caused extent these same changes are af the salmon in that wate.rfalls by local compaction of the sedi fecting the habitats of the dab which formerly obstructed their ments. Consequently, clam beds bling and diving ducks and the upstream migration were elimi which were once readily accessiblt trumpeter swans. nated. Along other streams, sub are no\V from 2 to 4 feet below low Brakish-water lagoons and mergence and flooding increased water and out of reach to conven sloughs are particularly favored as the size of the intertidal area. Re tional methods of harve8ting. nesting or feeding grounds by moval of waterfalls in some areas and enlargement of other areas, There is no general consensu8 as some wildfowl. Uplift drained thus increased the size and avail to wha1t long-term ecological effect some of these areas or made them ability of certain intertidaJ either submergence or emergence less brackish because of the inflow salmon-spawning grounds. has had upon the general clam or of fresh water. Thus, changed en W. L. Sheridan (written bivalve population within the af ''ironments, whether caused by up commun., 1965) stated that the fected areas. Certainly the initial lift or submergence, may ulti changes in the intertidal spawn mortality rate was high-es mately contribute to a decrease in ing habitat and environment have pecially in the uplifted areas-as the wildfowl population in specific not been fully assessed, but that was proved by the skeleton. In the areas. "'Whether new wildfowl com future production will decrease. submergent areas the greater munities will spring up in areas Although some intertidal spmwn depth of \Yater now present over made more favorable by the earth ing areas have increased in size, the outermost clam beds has also quake \vill not be known for some Sheridan indicates that many of resulted in bivalve mortality. years. EFFECTS ON SHORE PROCESSES AND BEACH MORPHOLOGY J19 EFFECTS ON PROPERTY VALUES AND MANMADE STRUCTURES Earthquake-caused uplift and after the earthquake when tides of emergence, it has also been subsidence--and the consequent were high. Several cannery necessary to relocate the installa changes in coastal processes~af wharves and loading platforms tions upon which barges, scows, feCJted the legalities of land owner had to be raised. In some places, and fishing boats -are stored in off ship, and also led to many changes such as at the \Vakefield Cannery sea.son months. At the beginning in property values and necessita at Port "\V akefield on Kodiak Is of the 1964 fishing season, follow ted reconstruction or relocation of land, complete relocation of the ing the earthquake, some craft had many coastal installations. A fe1w cannery was necessary. to be pulled from their storage of the resultant problems are In some submergent areas, wave areas onto the tidal flats by tractors touclwd on here. scour has moved la.rge quantities before they could be refloated. of gravel under or away from can SUBMERGENT AREAS neries and other facilities built LEGAL PROBLEMS As already mentioned, coastal over the high-,vater line. For ex Because the State of Alaska has erosion is occurring in many of the ample, a cannery at Larsen Bay on jurisdiction over the bottoms of submergent areas, and in some Kodiak Island, 'vhich was built in all navigable waters, legal prob a seemingly ideal location and was areas~such as on the Kenai Pe lems lmYe arisen wherever land ninsula~the rate of bluff recession adequately protected before the raised or lmvered by the earth is several feet per year. In other earthquake has incurred consider quake abuts navigable waters. In areas, erosion may still become a able storm damage since the earth Alaska the boundary of tidal problem although the process is quake. Erosion of gravel from the \Vaters is the line of mean high not yet noticeable. One such area adjoining beach has endangered tide. is along upper Cook Inlet where some of the cannery buildings. A person whose Alaskan prop submergence 'vas less than 2 feet. EMERGENT AREAS erty abuts the line of mean high The dramatic effects seen in areas tide is called an "upland owner." of greate!· submergence are not Some of the immediate effects By common-law principles the up present in this area, but there is of emergence that necessitated land owner enjoys all littoral unquestionably a gradual retreat economic and engineering consid rights and privileges afforded him eration were related to small-boat of the shoreline. This retreat is oc by the location of his land. Such harbors. In the Cordova area. the curring in some of the more, rights and pri l'ileges include, densely populated areas where lttnd was elevated about 8 feet. There emergence necessitated among others, free and unob land values are high. dredging and enlarging the small structed ingress and egress to the At Turnagain Arm, \vave ero boat harbor. Some of the channels se1a. sion has damaged road and rail of the Copper River Delta that The line of mean high tide thus road embankments that were had formerly been accessible to is the legal boundary that sep raised after the earthquake. \Vave fishing boats required considerable arates the upland owner's private erosion in that area will probably redredging in order to afford ac property from the State-owned continue, and the embankment will cess after the earthquake. In some tidelands. The line of mean high require constant surveilla.nce and uplifted areas, individuals who tide remains fixed unless the shore Jmtintenance. In Homer, wave formerly had access to the sea by line is altered by accretion or ero action has already damaged sec shallmY channels or tidal sloughs sion. If these processes result from tions of the newly constructed found it necessary to dredge their natural causes and the shoreline Homer Spit highway. access routes. In other areas, land changes are gmdual and imper Some shore installations that ing facilities, such a.s docks and ceptible, the legal boundary will escaped severe damage at the time wharves, could no longer accom change location to match the line of the earthquake were, because of modate deep-draft vessels and had of mean high tide. However, if the the higher stand of the sea, endan to be enlarged or relocated. changes are natural but sudden in gered by flooding a few weeks In Cordova, because of the 8 feet character and wholly perceptible, J20 ALASKA EARTHQUAKE, MARCH 27, 1964 the process i:s termed "avulsion," (State of Al:aska Attorney Gen. who enjoyed all the rights and and the legal boundary remains Opinion 6, Sept. 14, 1964). privilege.s afforded them :as upland fixed even though the mean high Along the uplifted coasts many owners befiore the earthquake now tide line has been displaced. private parcels of land abutted the find themselves una!ble to exercise Movement of the land during the line of mean high tide before the their littoral rights and privileges. earthquake was :rubrupt, certainly earthquake; afterwards, however, The opposite has occurred in the occurring within a matter of hours the natural line of mean high tide submergent areas. There, owners if not of minutes, and flooding or was shifted sea1ward, in some pl:aces of land that abutted the line of withdrawal of waters from the several hundred feet. Because mean high tide prim to the earth land was equally abrupt. On Sep withdrawal of the water has been tember 14, 1964, the attorney gen quake now find their boundary line eral for the State of Alaska de defined as avulsion, the priva.te ( t1hat is, the preearthquake line of scribed this process as one of ownership cannot follow the re mean high tide) some distance sea avulsion and therefore the legal treating line of mean high tide but ward of the natural mean high tide boundary line--the line of mean. must instead remain fixed to the line. These persons in fact own high tide-remains fixed as it was line existing the inst1ant before the tidelands hut the la,nds are legally the insta.nt before the eadhquake earthquake. Thus those persons described as uplands. NEED FOR FURTHER STUDIES One danger in attempting to probably did not allow for full such areas, the result more often rectify coastal-erosion problems is consideration of design methods than not promotes rather than re that protective measures are often with respect to unnatural slopes; tards wave erosion. taken without a clear understand such slopes can promote wave ero The installation and construc ing of littoral conditions. This sion. Time did not always allow tion of shore protective works will problem has already manifested for adequate investigation of near undoubtedly become necessary itself at various localities where shore conditions, such as wave long before a profile of equilibrium inst.allations that were constructed runup and current directi'On; con de.-elops and stabilizes-a profile to protect the land have in fact sequently, adequate safeguards to which will itself eventually retard destroyed it. insure maximum protection shoreline erosion. Therefore, the Some of the later damage to against coastal erosion were not eeonomic ramifications of coastal I'Oa:ds and embankments may per designed. CerttLinly, in the submer erosion not now readily noticeable haps be explained by the rather gent a:reas the sea has encroached may, within the next few years, be hurried reconstruction effort im upon the la.nd establishing a new come a problem which must be media:tely following the earth profile of equilibrium. When arti dealt with if valuable areas of land quake. The necessity for haste ficial impediments are placed in are to be saved. REFERENCES CITED Alaska Department of Fish and Game, Bruun, Per, 1962, Sea-level ri~e aR a Fisher, R. L., 1955, Cuspate spits of St. 1965, Post-earthquake fisheries cause of shore erosion: Am. Soe. Lawrence Island, Alaska: Jour. evaluation; an interim report on Civil Eng. Proe., v ..88, paper 3065, Geology, v. 63, no. 2, p, 133-142. the March 1964 earthquake effects .Jour. ·waterways and Harbors Div., Guilcher, Andre, 1958, Coastal and sub on Alaska's, fishery resources: no. WW 1, p, 117-130. marine morphology [translation by Juneau, Alaska, 72 p. Bird, E. C. F., 1964, Coastal landforms; Coulter, H. W., and ::\'ligliaccio, R. R, B. W. Sparks and R. H. W. an introduction to coastal geomor 1966, Effects of the earthquake of Kneese] : New York, .John ·wiley phology with Australian examples: March 27, 1964, at Valdez, Alaska: and Sons, Inc., 274 p. Canberra, Australian Natl. Univ., U.S. Geol. Survey Prof. Paper 542- Johnson, D. W., 1919, Shore processes 193 p. C, p. C1-C36. and shoreline deveolpment: New EFFECTS ON SHORE PROCESSES AND BEACH MORPHOLOGY J21 York, John Wiley and Sons, Inc., Plafker,, George, 1967, Surface fauHs on Terznghi, Karl, and Peck, R. B., 1948, 584 p. :\Iontague Island associated with Soil mechanics in engineering prac Kachadoorian, Reuben, 1965, Effects of the 1964 Alaska earthquake: U.S. tice: ~ew York, John ·wiley and the earthquake of March 27, 1964, Geol. Survey Prof. Paper G43-G, p. Sons, Inc., 566 p. at Whittier, Alaska; U.S. Geol. Sur G1-G42. Thorsteinson, F. Y., 1964, Effects of vey Prof. Paper 542-B, p. B1-B21. ---1968, Tectonics of the March the Alaska earthquake on pink and Kachadoorian, Reuben, and Plafker, 27, 1964, Alaska earthquake: U.S. chum salmon runs in Prince Wil George, 1967,' Effects of the earth Geol. Survey Prof. Paper i343-l. (In liam Sound: U.S. Bur. Commercial quake of March 27, 1964, on the press.) Fisheries Bioi. Lab., Auke Bay, communities of Kodiak and nearby Alaska, 16 p. Plafker, George, and Kaehadoorian, islands: U.S. Geol. Survey Prof. Twenhofel, "\Y. S., 1952, Recent shorp Reuben, 1966, Geologie effects of Paper 542-F, p. F1-F41. linp changes along the Pacific coast the March 1964 earthquake and m; Karlstrom, T. N. V., 1964, Quaternary of Alaska: Am ..Jour. Sci., v. 250, sociated seismic sea waves on Ko geology of the Kenai Lowland and no. 7, )J. ii23-i348. diak and nearby islands, Alaska : glaCial history of the Cook Inlet C.S. Coast and GPodetic Survey, 1964, U.S. Geol. Survey Prof. Paper 543- region, Alaska: U.S. Geol. Survey Prince ·william Sound, Alaskan D, p. D1-D46. Prof. Paper 443, 69 p. earthquakeN, :\Iarch-April 1964: King, C. A. M., 1959, Beaches and Plafker, George, and Rubin, :\feyer, U.S. Coast and Geod. Survey, Seis coasts : London, Edward Arnold and 1967, Vertical tectonic displace mology Div., Prelim. Rept., 83 p. Co., 403 p. ments in south-central Alaska dur Waller, R. :\I., 1966a, effects of the Kirltby, M. J., and Kirkby, A. V., 1968, ing and prior to the great 1964 ParthquakP of :\larch 27, 196-!, in Erosion and dePQsition on a beach earthquake : Jour. Geoscience, the Homer arPa, Alaska, 1cith a sec raised by the 1964 earthquake, Mon Osaka City Univ., v. 10, art. 1-7, tion on Beach changes on Homer tague Island, Alaska: U.S. Geol. p. 53-66. Spit, lJy K. W. Stanley: U.S. Geol. Survey Prof. Paper 543-H. (In Sunpy Prof. Paper 542-D, p. D1- Reimnitz, Erk., and :\larshall, N. F., press.) D28. Lobeck, A. K., 1939, Geomorphology ; 1965, Effects of the Alaska earth --- 1966lJ, }]ffects of the :\[arch 1964 an introduction to the study of quake and tsunami on recent deltaic Alaska earthquake on the hydrol landscapes: New York, McGraw sediments: Jour. Geophys. Re ogy of south-central Alaska: U.S. Hill Book Co., 731 p. search, v. 70, no. 10, p. 2363-2376. Geol. Surny Prof. Pappr 544-A, p. Noerenberg, W. H., and Ossiander, F. J., Schwartz, ::\faurice, 1965, Daboratory A1-A28. 1964, Effects of the March 27, 1964, study of sea-level rise as a cause Wood, F ..J., ed., 1966-67, The Prince earthquake on pink salmon alevin of shore erosion: Jour. Geology, v. "\Villiam Sound, Ala~;lm, earthquake survival in Prince William Sound of 1964 and aftershocks: U.S. Coast 73, no. 3, p. 528-534. spawning streams: Alaska Dept. and Geod. SurvPy Pub. 10-3, v. 1, Fish and Game Inf. Leaflet 43, 10 p. Stanley, K. W., and Gre~·, H. J., 1966, 1966, 236 p. ; v. 2, pt. A, 1967, 391 p. Plafker, George, 1965, Tectonic defor Spray-on paint stripes to determine Zenkoviteh. V. l'., 1951), On the genesis of mation associated with the 1964 the directlion of beach drifting : euspa te spits along lagoon shores : Alaska earthquake: Science, v. 148, Jour. Geology, Y. 74, no. 3, p. 357- .Jour. Geology, v. 67, no. 3, p. 269- no. 3678, p. 1675-1687. 361. 277. The Alaska Earthquake March 27, 1964: Regional Effects This volume was published as separate chapters A -J GEOLOGICAL SURVEY PROFESSIONAL PAPER 543 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director CONTENTS [Letters designate the separately published chapters] (A) Slide-induaed waves, seiching, and ground fracturing caused by the earthquake of l\larch 27, 1964, at Kenai Lake, Alaska, by David S. McCulloch. (B) Geomorphic effects of the earthquake of March 27, 1964, in the Martin-Bering Rivers area, Alaska, by Samuel J. Tuthill and Wilson M. Laird. (C) Gravity survey and regional geology of the Prince William Sound, epicl'ntral region, Alaska, by J. E. Case, D. 1!''. Barnes, George Plafker, and S. L. Robbins. (D) Geologic effects of the March 1964 earthquake and associat!'d ~!'ismic ~ea waves on Kodiak and nearby islands, Alaska, by George Plafker and Reuben Kachadoorian. (E) Effects of the earthquake of March 27, 1964, in the Copper Rin•r Basin area, Alaska, by Oscar J. Ferrians, Jr. {F) Ground breakage and associated effects in the Cook Inlet area, Alaska, resulting from the March 27, 1964, earthquake, by Helen L. Foster and T'hor N. V. Karlstrom. (G) Surface faults on Montague Island as,;ociated with tlw l!l64 Alaska earthquake, by Georg!' Plafk!'r. (H) Erosion and depos:ition on a beach rais!'d b~· the ll)'M !'arthquake. :\[ontagn!' Island, Alaska, by :\f. J. Kirkby and Anne V. Kirkby. (I) Tectonics of the March 27, 1964, Alaska earthquake, by Georg!' Plafker. (J) Effects of the Alaska earthquake of :\larch 27, 19fJ4, on shore processe,; and b!'ach morphology, by Kirk \V. Stanley. U.S. GOVERNMENT PRINTING OFFICL 1968 0-298-580 ,...... ,...... C'? c.-> c.-> <=.... -"'