Effects on Hydrologic Regimen

Glaciers

r,FQLOGICA SURVFY PROFFSSIONA PAPER 544-D

This page intentionally left blank THE ALASKA EARTHQUAKE, MARCH 27,1964: EFFECTS ON THE HYDROLOGIC REGIMEN

Effects of the March 1964 Alaska Earthquake on Glaciers

By AUSTIN POST

GEOLOGICAL SURVEY PROFESSIONAL PAPER 544-D UNITED STATES DEPARTMENT OF THE INTERIOR

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY

William T. Pecora, Director

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1967

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 45 cents THE ALASKA EARTHQUAKE SERIES

The U.S. Geological Survey is publishing the results of investigations of the Alaska earthquake of March 27,1964, in a series of six Professional Papers. Professional Paper 544 describes the effect on hydrology. Other Professional Papers, some already published and some still in preparation, describe the effects of the earthquake on communities; the regional effects of the earthquakes; the effects on transporta­ tion, communications, and utilities; and the history of the field investigations and reconstruction effort.

CONTENTS

Page Pap;e Page Abstract ... D1 Earthquake-induced rockslide Changes m drainage and flow of Introduct.IQn 1 avalaniJhes on glaciers Con glacially fed rivers due tQ the Acknowledgments 2 Smaller avalantJhes TCon 1964 earthquake D33 Possible effects of earthquakes Allen Glacier_ . D21 Effects of the 1964 tectomc dis- . 6n glaciers. 2 Fickett Glacier_ _ _ . 21 placement.s on glaciers 34 Snow avalaMhmg .. 3 Unnamed glacier near Direct effects of the 1964 earih- Ice avalanching 5 Paguna Bay 21 quake on titial glaciers 36 Earthquake-intiuced roiJkslide Ro~Jkslide avalanches not asso­ Interpretatio11 of the data 36 avalaniJhes on glaciers 6 ciated with the 1964 earth­ Effect of avalanche-caused Sherman Glacier. 6 quake. _. 26 truckemng OTJ! the flow of Schwan Glacier .. 13 Avalanches before the 1964 gladers 36 Bermg and Steller Glaciers 13 earthquake._ 26 The earthquake-advance Martm River Glacier. 13 Rockshde avalaniJhes since theQry 37 Sioux Glacier 13 August 1964 26 Glacier surges 38 Smaller avalaniJhes . 21 General characteristics of the Summary anti conclusions 41 Saddlebag Glacier 21 larger rockslide avalaniJhes .. 31 References 41

ILLUSTRATIONS

FIGURES

Page Page Pa!'e 1. Map of sQuth-central Alas­ 10. S1Jhwan ·Glamer on August 18. Allen Glamer rockslide ava- ka vi 26, 1963 D14 lanche 1, August 25, 1965. D23 2. Head of Meares Glader, 11. Schwan Glader on August 19. Crulds Gleder, August 26, August 24, 1964 D4 25, 1964___ 15 1963.- 24 3. Cliffs on south side of Har­ 12. Map of rockslide avalanches 20 Childs Glacier, August 25, vard Glacier, August 24, in the W axell Ridge region, 1965.. 25 1964 ... 5 Fering anti Steller Gla- 21. Allen roiJkslide avalaMhe 4, 4. Honzoni,al profiles of roiJk­ ciers. . _ _ _ HI August 25, 1965 27 slide avalaniJhes on gla­ 13. Map of roiJkslide avalaMhes 22. F.ockslide avalanche on Fair­ ciers. . . _ . - 7 on the Martin River an<:l weather Glacier, August 5. Map of rockslide avalanches western Steller Glaciers . _ 1 7 22, 1965.. 29 in the Sherman and Sad­ 14. Map of rollkslide avalanches 23 Map of rockslide avalaniJhe dlebag Glaciers area.. 8 and rockfalls m the Sioux, 011 Fairweather Glacier ' 30 6. RQIJkshde avalantJhe on Sher­ Johnson, and Miles Gla 24 RotJkslide avalanllhll on Net- man Glacier, August 25, mer region 18 land Glacier, August 29, 1965 .• 9 11). SiQux Glacier, August 26, 1964 32 7. Sherman Glacier, August 26, 1963 and August, 24, 1964. 19 25. Map showing relat10n of 1963 ______·-----·- 10 16. Saddlebag Glacier, August earthquake subsidence anti 8. Sherman Glacier, August 24, 26, 1963 anti August 25, uplift to glaciers _ 35 1964. ··-- 11 1965 20 26. Observed glacier surges smre 9. Map of rockslide avalanche 17. Map of rockslide avalanllhes 1936 in Alaska and western on Schwan Glacier. 12 on Allen Glacier_ _ _ _ _ 22 Canada. 40

TABL~JS

Pap;e I. Snow avalaMhes on large glaciers near the epiceni,er of the 1964 earthquake D4 2. Earth'luake-mduceti rockshde avalaniJhes 6 3. Rockshde avalanche deposits on glaciers since 11}45 and pnor to 1964 earthquake 26 4. Rockslide avalanr,hes more recent than 1964 earthquake 26 5. Late August levels of glamllr-dammed lakes m the Chugach and Kenai Mountams, 19RO 65 33 6 Changes in termmi of tidewater glaciers in the Chugallh and Kenai Mount.ams, 1960 65 31) 7. Lengths anti times of sudden movement of glaciers observed by Tarr and Martin llfter the 1899 earth quake 39 v 138° 0 50 100 MILES

0 50 100 KILOMETERS

0 F Yakutat G U L F ALASKA

EXPLANATION ~Bagley All enD

Icefields and glaciers Limit of cracking of alluvial deposits Epicenter of 1964 earthquake Glacier areas shown as figures and photographs in this report

FIGURE 1.-Map of south-central Alaska showing the major glaciers and icefields and the epicenter of the March 27 earthquake.

VI THE ALASKA EARTHQUAKE, MARCH 27,1964: EFFECTS ON THE HYDROLOGIC REGIMEN

EFFECTS OF THE MARCH a964 ALASKA EARTHQUAKE ON GLACIERS

By Austin Post

ABSTRACT

The 1964 Alaska earthquake occurred occurring in the Copper River region scale dynamic response of any glacier in a region where there are many 160 kilometers east of the epicenter. to earthquake shaking or avalanche hundreds of glaciers, large and small. Some of these amlanches traveled sev- loading was found in either the Chugach Aerial photographic investigations in- eral kilometers at low gradients; com- or Kenai Mountains 16 months after dicate that no snow and ice avalanches pressed air may have provided a lubri- the 1964 earthquake, nor was there any of large size occurred on glaciers despite cating layer. If long-term changes in evidence of surges (rapid advances) as the violent shaking. Rockslide ava- glaciers due to tectonic changes in alti- postulated by the Earthquake-Advance lanches extended onto the glaciers in tude and slope occur, they will probably Theory of !L'arr and Martin. many localities, seven very large ones be very small. No evidence of large-

INTRODUCTION

Alaskan glaciers are of such size Most rivers in this area derive a The author conducted aerial- and number that they influence the part of their flow from glaciers, photographic investiga1;ions on climate, streamflow, and works of and, for many major streams, such glaciers in northwestern North man in many parts of the State. as the Matanuska and Copper America from 1960 to 1963 under Their influence is especially im- Rivers, glacier melt provides a grants from the National Science portant in the region most strongly substantial part of their summer Foundation. This project was runoff. Although it is primarily administered by the University of affected by the Alaska earthquake the glacial rivers that affect works Washington, Seattle, P. E. Church of March 27,1964, where about 20 of man in the State, in a few places being principal investigator. percent of the land area is covered the glaciers themselves are near Practically all of the larger gla- by ice (fig. 1). North, east, and transportation routes or facilities. ciers in Alaska were examined and west of the epicenter, the Chugach Changes in glaciers resulting from their various features noted. More Mountains are covered with ap- earthquakes thus may have eco- than 2,000 oblique and vertical proximately 6,500 km2 (square nomic as well as scientific interest. photographs were taken each year. kilometer) of icefields and snow- The 1964 earthquake was one of These observations and pictures filled valleys from which more the strongest ever recorded in provide detailed information than a dozen major and hundreds North America. Tectonic dis- about the glaciers before the earth- of s m a 1 1e r glaciers descend. placements occurred over a larger quake occurred. Southwest of the epicenter the area than has previously been ob- The U.S. Geological Survey Sargent and Harding Icefields served (Plafker, 1965a; Plafker continued these studies in 1964 and Mayo, 1965). The area in and 1965 as part of n broader and other glaciers cover approxi- which cracking occurred in allu- program of investigation of the mately 4,200 krn2 in the Kenai vial deposits is considered the relation of glaciers to climate and Mountains. East of the Copper probable limit of the area where the role of glaciers in the hy- River, the Bagley Icefield con- noticeable effects on glaciers might drologic cycle. Mark F. Meier tains some 10,400 km2 of glaciers. be expected (fig. 1). directed this program. Dl D2 ALASKA EARTHQUAKE, MARCH 27, 196:4

By comparing photographs m o r a i n e s, superglacial photographs were furnished the taken before and after the earth- streams and lakes. author by George Plafker of the quake, the immediate effects on Glacier termini-position, Geological Survey and Troy glaciers can be analyzed. The configuration, and relative P6w6 of the University of data available make it possible activity. Alaska, John Sater of the Arctic to determine what changes have Iceberg discharge of tidal Institute of North America, and occurred in other years in the glaciers. W. 0. Field of the American shaken area. Changes in regions Outlet and marginal streams, Geographical Society. John R. where earthquake shaking did not and glacier-dammed lakes. Reid of the University of North take place were also analyzed. Terminal and lateral mo- Dakota, Colin Bull of the Ohio Studies were conducted in late rainos, trimlinw, and bar- State University, Institute of August and in September, the ren zones. Polar Studies, Samuel Tuthill of time when the seasonal snow In addition, a careful search was Muskingum College, Ohio, fur- cover on glacier ice is at a mini- made during the 1964 and 1965 nished information regarding mum. High-resolution aerial flights to find evidence of changes studies of Sherman and Martin cameras were used. The follow- in glaciers attributable to the Rivers Glaciers. Mark Meier of ing glacier features were visu- earthquake. the Geological Survey discussed ally examined and photographed : the probable effects on glaciers of Firn line and snow cover. ACKNOWLEDGMENTS avalanches and tectonic displace- Snow, ice, and rock ava- This study was made possible ments. TV. R. Fairchild, Don lanches. by utilizing aerial photographs Sheldon, and Jack Wilson pro- Extent of crevassing and evi- taken for the National Science vided skilled piloting on aerial dence of changes in glacier Foundation in 1960, 1961, and photographic missions. D. R. thickness and rate of flow. 1963 under contract with the Crandell of the Geological Sur- Surface features including University of Washington, Seat- vey and W. 0. Field critically ogives, icefalls, medial tle, Wash. Information and (or) reviewed the manuscript.

POSSIBLE EFFECTS OF EARTHQUAKES ON GLACIERS

Earthquakes and changes in the adjacent slopes onto man, 195'7) and a possible advance surface of the earth related to glaciers. of the terminus. Sudden spectac- earthquakes can affect glaciers in b. Rockfalls and rockslide ular glacier advances after the many ways. The glaciers can be avalanches from ad- severe 1899 earthquake were re- made thicker or thinner, the land jacent slopes onto ported by Tarr and Martin surface can be so deformed as to glaciers. (1914) ; they attributed the ad- cause changes in net mass budget c. Decreased melting due to vances to extensive earthquake- (difference be tween accumulation insulation of ice pro- induced avalanching of snow and and ablation of snow and ice) or vided by heavy ac- ice onto the glaciers. Less in the slope of the glaciers, glaciers cumulations of dust or spectacular effects of increased ice which calve off into water can be rock debris on glaciers. thickness might be a slowing of the affected by shaking or by changes d. Decreased melting due to glacier retreat, stability, or a slow in the water body, and the glacier increased albedo (solar advance of the terminus. ice may be directly affected by radiation reflectivity of shaking. Seven possible changes the surf ace), caused by 2. Decreased ice thickness result- are : accumulation of clean ing from accelerated melting due avalanche snow and ice to decreased albedo, caused by a 1. Increased ice thickness result- over dirty ice. thin surf ace layer of dust and rock ing from : Increased ice thickness on debris. Reduced ice flow, slowing a. Extensive avalanching of glaciers results in accelerated of advance, stagnation or retreat ice and (or) snow from glacier motion (Nye, 1952; Weert- of the terminus, or even complete EFFECTS ON GLACIERS disappearance of the glacier are these streams were affected by shaking to cause appreciable possible effects of thinning. earthquake-induced changes in changes in glacier flow rates by glaciers. either of these phenomena. Inas- 3. Disruption of glacier-fed rivers much as no observational data on by : 4. Change in flow characteristics either mechanism are available, of glaciers due to shaking. Sud- these phenomena are con~idered a. Glacier advance, blocking den advances of glaciers have been purely hypothetical and are not the normal course of reported where no snow and ice discussed further in this report. streams or rivers and avalanching have been observed. forming 1 a k e s, which The possibility that earthquake 5. Breakup of the terminus of may be followed by a shaking of unstable glaciers di- tidewater glaciers due to shaking. sudden release of water rectly results in such advances has Accelerated discharge of icebergs when such glacier dams been considered (Post, 1960). and possible retreat of the glacier burst or are overtopped Such advances might result from: might result. and rapidly disintegrate. a. Changes within the struc- b. Closing or opening of en- ture of the glacier ice 6. Changes in lthe terminus of tide- glacial or marginal chan- that alter its flow-law water glaciers due to vertical nels resulting in the im- properties and, in conse- movement of ,the land. Advance poundment or release of quence, the speed of in- of raised glaciers and retreat of runoff. ternal deformation of the lowered glaciers are possibilities. Highways parallel the Matan- glacier. uska and Copper Rivers, and b. Changes in the properties 7. Long-term changes in mass or transportation routes follow rivers of the boundary layer be- flow characteristics of glaciers or in the Kenai Mountains. In addi- tween the glacier and its both, due to change in altitude or tion, major ports, such as Seward bed that alter the rate at slope caused by tectonic displace- and Valdez, are near the mouths of which the glacier slides. ment. Effects may be greater or glacier-fed rivers. Severe dam- The author knows of no physical less, depending upon the magni- age could result from flooding if mechanism which would permit tude of the changes.

- -- SNOW AVALANCHING

The 1964 earthquake occurred at Because of the unstable snow Ragle and others (1965a, p. 2) a time of year when large quanti- conditions mentioned by La- made reconnaissance flights be- ties of snow were present on gla- Chapelle, major avalanching onto tween April 9-19 and September ciers, and avalanche hazard was the glaciers might have been ex- 4-24, 1964, and summarized their high in some areas. E. R. La- pected during the earthquake. findings as follows: Chapelle, snow avalanche special- However, George Plafker (writ- The scarcity of obvious change was ist with the U.S. Forest Service, ten commun., 1964) found little surprising because the glaciers must have been shaken violently by the earth- stated (oral commun., 1966) : evidence of snow avalanches on quake. There were few snow ava- the glaciers during flights made lanches or snow slides in the glacier The Good Friday earthquake oc- basins and none of them appeared to curred during a period of known nat- March 29 and April 6, 1964. He wrote : have added enough substance to af- ural avalanche hazard in the Chugach fect glacier regimen appreciably * * *. Mountains in the vicinity of Anchorage With a few exceptions, hanging glaciers and Turnagain Arm. The snow cover My general impression gained from the reconnaissance flying is that the did not appear to have been affected at this time was recorded as unstable. volume of snow shaken down by the and there was no unusual calving of For this reason, the Forest Service glacier termini into tidewater. ranger on duty at Alyeska Ski area earthquake is inflnitely small relative to the size of the drainage basins of closed parts of that area to public use Photographs taken April 1, the coastal glaciers. I seriously doubt a few hours prior to the earthquake. 1964, by T. L. P6w6 show the The subsequent occurrence of ava- that the amount of snow observed in lanches in this and other nearby areas these avalanches could have a signi- termini of Meares, Yale, Har- indicates that the hazard prediction was ficant effect upon the regimen of any vard, and Columbia Glaciers. No correct. of the glaciers I saw * * *. evidence of avalanching is shown. D4 ALASKA EARTHQUAKE, MARCH 27, 1964

FIGURE2.-Head of Meares Glacier, August 24, 1964. The snow avalanches, which may have resulted from the March 27 earthquake, are shown by arrows.

Furthermore, no evidence of TABLE1.-Snow avalanches on large glaciers near the epicenter of the 1964 earthquake

significant avalanching of ice or Distance from epicenter snow was found during the au- Glacier Area of glacier Approximate area Ikm9 of snow av- Direction 1 1 alanches (kmz) thor's investigations in August 1964. Traces of large winter Columbia- _ ------25 NE------1,370 or spring snow avalanches can Meares--__------..---- 23 NNE-_------__- 135 Yale------26 N------225 usually be detected on glaciers as Haward-_------35 N 505 late as August because of differ- ing snow texture, streaks of fine debris, or the obscuring of gla- duced avalanches of snow found Evidence of snow avalanching cial structures. All of the larger on these glaciers are summarized has been found each gear the glaciers in the Chugach Moun- in table 1. glaciers have been examined. The amount of avalanching in 1964 tains were observed. Detailed On the Columbia Glacier, evi- was not, in general, more than oblique photographs wcre taken dence of snow avalanching was so that usually detected. All observ- of the precipitous slopes adjacent minor that no more avalanches ers' reports and the evidence seen to the Columbia, Meares, Yale, were noted than are shown in pho- in August 1964 indicate that and Harvard Glaciers, all of tographs taken in other years. A snow avalanching resulting from which are near the epicenter (fig. few small snow avalanches oc- the earthquake was not great 1). The areas of these glaciers curred near the head of Meares enough to materially affect any and the areas of earthquake-in- Glacier (fig. 2). glacier's regime. EFFECTS ON GLACIERS ICE AVALANCHING

Large-scale avalanching of ice The ice-sheathed cliffs near the ice avalanching was noted ad- from hanging glaciers and ice- head of Harvard Glacier are jacent to the Yale Glacier. veneered cliffs adjacent to large among the most extensive and Although some steep ice on glaciers could materially affect a steepest in the Chugach Moun- slopes had an unusually shattered few glacier regimes. The glaciers tains. Many small avalanches oc- appearance after the earthquake were carefully scrutinized in curred on the south side of the (Nielsen, 1965), no ice avalanches August 1964 to determine if ice glacier (fig. 3), but only two wece mere found that were large enough avalanching had taken place. large enough to leave conspicuous to materially affect any glacier's deposits. No evidence of extensive regime.

FIGUBE3.-Cliffs on south side of Harvard Glacier, August 24, 1964. Sliding of snow has taken place on these slopes, as shown by the avalanche paths and filled crevasses on the left and by the avalanche debris at the foot of the cliffs in the center of photograph. However, hanging glaciers on these cliffs apparently were little affected 'bythe earthquake. ALASKA EARTHQUAKE, MARCH 27, 1964

EARTHQUAKE-INDUCED ROCKSLIDE AVALANCHES ON GLACIERS

Apparently the most important TABLE2.-Earthquake-induced rockslide avalanches effect of the 1964 earthquake on [Slide area: more important slides in italic] glaciers has been the change in Glacier Avalanche their regime resulting from rock- -- slide avalanches. Rockfalls oc- Slides Lon i curred over a very broad area as a Name Area (kmz) No. Latitude tud- No. Area Mgth Direction result of the earthquake. This rn2) (km) traveled ------distribution is not a simple func- 0, 0, tion of distance from the epicenter, Sherman ..57 -- 1 60 33 145 10 1 8.6 6 NW. 2 33 06 1 1.5 2.5 N. but is related to local structure and 3 31 08 1 1.5 3 N. 4 32 10 1 1.5 NE. weakness in bedrock. Direction 8hw1 .. 1 60 a 145 11 1 d 6 NNW. 2 57 08 1 1.5 w. of avalanche movement apparently Martin River -.--.-280 ---...------1 60 38 143 36 1 i 3 NNW. 2 36 38 2 11.6 4 NW. was controlled by local topog- 3 38 35 2 6.5 5 8 88E. 4 37 39 1 18.5 5 8b~. 5 34 38 1 1.5 3.5 8W. raphy, no particular direction of 6 33 44 1 1 2.5 8. movement predominating. Most Bin.. 5 1 60 32 143 17 1 3 5 8. 2 30 10 1 2.5 6.5 8. 3 28 06 1 2.5 5 8. of these rockfalls and rockslide 4 28 04 1 1 1.5 88E. 5 28 142 n 1 1.5 2.5 N. avalanches were minor in both size Steller-.--.-....-.- Branch of Bering 1 60 36 143 17 1 7.6 6.5 N. Glacier. 2 33 31 1 1 2.5 8E. and importance. 3 33 32 1 .5 2.6 88E. 4 32 34 1 1 4 88W. Rockslide avalanches which oc- 6 32 39 1 1 2.5 8. Sioux.. 1 60 32 144 19 1 S 4.5 8. curred between August 1963 and 2 34 18 5 1 1 1NW,38W, 1 BE. August 1964 that were observed by a 32 1s 1 1 1 NW. on-- %. -- 60 34 144 21 4 2.5 2.5 1W,3NW. the author are listed in table 2. Unnd8.- -- 60 36 144 21 2 1.5 1.5 N 8E. Van lee-- 62 - -- 60 M 144 13 2 1 1 N: The location and area of the 81.- 1 -- -- 60 31 145 06 4 2.5 2.5 188E 2 SW, 1 NE: glaciers and of all rockslide ava- Fickett ..3.. - 60 33 145 01 1 1 3 NNE. A ..0 .. 1 60 46 144 60 1 2 3 N. lanches of more than 0.5 km2, to- 2 45 45 1 1 2.5 NW. 3 47 55 1 1 1.5 N. gether with the general direction Scott ..1 -- -- 60 43 145 08 3 1.5 1 8E. Rude.- 26 ------1 60 47 145 11 1 2 5 NW. of movement of the avalanche, are 2 47 08 1 1 2 NW. a --31 .. -- 61 02 145 27 1 1.5 2.5 WNW. listed. C01~mb-- 1,370.. 1 61 13 147 14 1 1 1.5 8W. 2 13 16 2 1 1.5 E8E. Several very large rockslide ava- Re.. 4 -- -- 61 11 147 34 1 1 2 8E. Set 26 .--- 61 09 148 16 1 .5 2.5 8. lanches occurred at the time of the 06 18 1 .5 2 E. 8 ..70 -- -- 61 02 148 31 2 3 3 E8E. earthquake. Profiles of these ava- H --49 -- -- 60 56 128 28 2 1 2.5 N. PO-- 16-- -- 60 64 148 30 1 .5 4 E. lanches are shown on figure 4. Twentymile-. 49 .- 1 60 57 148 38 1 2 2.5 W. 2 56 38 3 1.5 151W2NW. Individual rockslides are described Cot.. 1 .. - 60 28 148 28 4 3 1: 5 NE.' Unnamed --..-.---11-.-.----..------.59 48 149 57 3 1.5 1.5 W. below. Do4 -- 59 42 150 03 2 2.5 1.5 W, SW. DO-- 4- -- 59 44 1M) 15 1 .5 1.5 E.

SHERMAN GLACIER 1 ~ust. The Sherman Glacier (figs. 4A, 5) received one very large rock- slide avalanche and several smaller ones at the time of the the ablation area of the glacier, thickness of 5 m (figs. 6, 7, 8). earthquake. The largest of these, is 5.6 km long, as much as 4 It has been computed h;y George which covers about 50 percent of km wide, and has an average Plafker (1965b) to contain about EFFECTS ON GLACIERS D7

METERS

•= ~ A__ s_h_e_r_m_a_n_l ____ _ o~, ~ 0 2000 4000 6000 METERS

2000

Schwan 1

1000

0~----,-----,----,-----,----,-----,

2000 c Steller·!

1000

0~----,-----,-----,-----,-----,-----,----,

1ooo~ n ~-s-~_·o_u_x___ _

0

2000

Allen 4 1000 t:E------0 ,_-----,-----,------,-----,------,-----,------.-----~

4000

3000 F Fairweather

2000

1000

0~----,-----,-----,-----,-----,-----,----,-----,-----,-----, 0 2000 4000 6000 8000 10,000 METERS

FIGURE 4.--Horizontal profiles of rockslide avalanches on glaciers. Datum is mean sea level. ALASKA EARTHQUAICE, MARCH 27, 1964

EXPLANATION AVALANCHE DEBRIS

Probably 1 meter or more Small volume of dust and Source area of avalanche Direction of view shown thick containing rock fine rock debris in accompanying photo - fragments 3 meters or graph more long -----) (- __f 1 ---- Direction of movement Number of avalanche listed Ice-covered divide in an accompanying table

E"Ioum 5.-Map of rockslide avalanches in the Sherman and Saddlebag Glaciers area. EFFECTS ON GLACIERS D9

FIGURE6.Rockslide avalanche on Sh@rman Glacier. The source was from the area marked by the fresh scar on Shattered Peak in middle distance. The debris displays flowlines and terminal digitate lobes. No marginal dust layer is present. The steep margin, about 20 m above the clear ice, is due to more rapid melting of the exposed glacier than the ice pro- tected by the debris (see figs. 4A, 5,7,8). Photograph taken on August 25,1965. Dl0 ALASKA EARTHQUARE, MARCH 27, 1964

Fraum 7.-Sherman Glacier on August 26, 1963, showing conditions before the earthquake; compare with figure 8. EFFECTS ON GLACIERS Dl1

FIGURE8.-Rockslide avalanche oil Sllerlllan Glacier. The avalanche was formed by the co1lul)se of Shattered l'eak ill tlle middle distance. The debris shonrs flowlines and terminal digibate lobes. No marginal dust layer is present. View look- ing southeast. Photograph taken August 24, 1964. EXPLANATION AVALANCHE DEBRIS - Probably 1 meter or more Small volume of dust and Source area of avalanche Direction of movement thick containing rock fine rock debris fragments 3 meters or more long 1 Direction of view shown in Number of avalanchelisted accompanying photograph in an accompanying table

Roum 9.-Map of rocksllide avalanche on Schwan Glacier. EFFECTS ON GLACIERS

25 million m3 (cubic meters) of gime therefore should be relatively which received three major ava- shattered rock debris and minor s m a 1 1. Photographs taken in lanches (Tuthill, 1966). Together amounts of admixed ice and 1963, 1964, and 1965 show no ap- these probably contain about 24 snow. Practically all of this ma- parent dynamic change in the gla- million m3of broken rock. Three terial came to rest on the glacier cier between these d& (figs.-10, other avdanclles on this branch below the firn line. No marginal 11). appear to be little more than thin dust layer is present. Possible layers of dust. The avalancl~eson effects of the avalanches on the BERING AND STELLER this branch of the glacier are so glacier include reduced ablation, GLACIERS large that some dynamic response increased flow, and advance of the to the loading would seem likely. main glacier. With its major branch, the Stel- About 5 per.cent of the glacier sur- W. 0. Field of the American ler Glacier, the Bering Glacier face \\-as covered with rock debris. Geographical Society (written covers an area of about 5,800 kmz. As this material moves into the commun., 1966) has commented : Pour rockslide avalanches more ablation area, its effect will be to "The Sherman Glacier has re- than 5 km in length and several reduce ice melt. 9 medial mo- treated about 800 meters previ- smaller ones originated on Waxell raine near the center of the main ous to 1950, from forest trimlines. Ridge. T h e largest avalanche tributary of the glacier moved From August 5, 1950, to June (Steller 1) is 6.5 km in length, has down valley about 240 m between 1965, recession at the outermost a maximum width of 2 km, and August 1964 and August 1965. part of the t,erminus in the mid- probably contains at least 10 mil- dle of the valley totaled 375 lion m3 of rock. Because it lies SIOUX GLACIER meters, representing an annual well above the snowline and is The Sioux Glacier (unofficial average of 25 meters." However, therefore largely snow covered in name, Tuthill and others, 1964; by late summer 1965, an advance a11 pl~otographs,few details are Tuthill, 1966. Figs. 411, 14) re- of as much as 6 m in some parts known. From a maximum source ceived the greatest number of of the terminus may have oc- altitude of nearly 3,000 m, the rock rockslide avalanches, for its size, curred (M. T. Millett, oral com- debris descended slopes of about of any valley glacier (fig. 15). mun.). A push moraine about 5 43" for 600 In. 011 reaching the As a result, easily detectable m high had formed (W. 0. Field, nearly level glacier, .the material changes in the glacier's regime are oral commun.) Aerial photo- swept out with a gradient decreas- . anticipated. Long-term effects of graphs taken of the terminus in ing to less than 2" in the last 3 km the debris will be to reduce ice 1963 and 1964 show a small re- (fig. 4C). Snow on the upper treat between those dates; little parts of the other rockslide ava- melt, which will favor rejuvena- further change in the terminal lanches on Waxell Ridge obscures tion of 'the relatively inactive position of the glacier was noted source areas (fig. 12). Four terminal ice and may eventually in 1965. small avalanches occurred on the result in advance. Various The effect of the avalanche de- western part of the Steller Glacier features of the glacier are listed posit on the behavior of the glacier (fig. 13). below. and the mode of deposition of the No dynamic response to ava- avalanche debris are being investi- lanche loading has been noted in size Feu ture gated by Colin Bull of the Ohio any of the branches of Bering and (Rmr) Steller Glaciers where avalanches Accumulation area ------12 State University Institute of Area covered by debris- 2 Polar Studies (written commun., occurred. Long-term effects of Ablation area ------5 1966). the avalanche debris will be to re- Area covered by debris duce ice melt somewhat, but, rela- before earthquake---- 1 SCHWAN GLACIER tive to the size of these large gla- Area covered by debris after earthquake----- 4.5 Although the rockslide ava- ciers, this effect will be insignifi- cant. lanche (figs. 4B, 9) on Schwan About 17 percent of the ac- Glacier is one of the largest re- cumulation area of the Sioux MARTIN RIVER GLACIER sulting from the 1964 earthquake, Glacier was covered by rockslide it covers only about 15 percent of The Martin River Glacier (fig. debris. Little dynamic rasponse the ablation area of this large gla- 13) is fed by three major trib- to this loading could be found in cier. Its effect on the glacier's re- utaries, the most northerly of a comparison of vertical photo- - - -

ALASKA EARTHQUAKE, MARCH 27, 19 64

~ FIGURE 10.-Schwan Glacier on August 26, 1963, s~howingconditions before the earthquake; compare with figure 11. EFFECTS ON GLACIERS D 15

FIGUR~U.-Wkdide avalanche on Schwan Glacier. The source of the avalanche is the mountain peak behind and to the left of the debris A broad layer of dust surrounds the demt. View looking southwest. Photograph taken August 25,1984. ALASKA EARTHQUARE, MARCH 27, 19 64

P"Ioua~12-Map of rockdide avalianches in the Waxell Ridge region, Bering and Steller Glaciers. EFFECTS ON GLACIERS Dl7

EXPLANATION AVALANCHE DEBRIS

Probably 1 meter or more Small volume of dust and Source area of avalanche Direction of movement thick containing rock fine rock debris fragments 3 meters or more long 1 Number of avalanche listed ------) (------in qn accompanying table Firn line Ice-covered divide

FIGWBE13.-Map of rockslide avalanches on the Martin River and wastern Steller Glaciers. ALASKA EARTHQUAKE, MARCH 27, 19 64

EXPLANATION AVALANCHE DEBRIS

Probably 1 meter or more Small volume of dust and Source area of avalanche Direction of movement thick containing rock fine rock debris fragments 3 meters or more long

Direction of view shown Number of avalanche listed Firn line Ice-covered divide in accompanying photo- in an accompanying table graph

FIGURE14.-Map of rockslide avalanches in the region of Sioux, Johnson, and Miles Glaciers. FIGURE15.-Sioux Glacier on August 26, 1963 (left) and August 24, 19M (right). Nearly all of the ablation area of this glacier was covered by debris from large rockslide avalanches orginating on the peak on the left. Other smaller rockslides occurred at many places in the accumulation area (see fig. 14). Vims looking northwest. w D!N ALASKA EARTHQUAKE, MARCH 27, 19 64

FIGURE16.-Saddlebag Glacier on August 26, 1963, showing conditions before the earthquake (above) and on August 25, 1965, showing conditions after the earthquake (below). Note the change in Shattered Peak. View looking north. EFFECTS ON GLACIERS graphs taken in August 1964 and discharge into the lake is likely has remained stagnant. The sec- August 1965. Some slight in- because of the decreased melting tion where ice is exposed appeared crease in crevassing in the area of resulting from the avalanche smooth and almost inactive in the firn line may have taken place. debris. 1961 ; there were more crevasses in 1963. The 1964 observations dis- After the earthqualrc, nearly ALLEN GLACIER 90 percent of the ablation area closed an advance of about 300 m of this glacier was covered with Three rockslide avalanches during the previous year; in 1965 debris. Tuthill (1966) estimated were noted in 1964 on Allen an advance of an additional 300 m the avalanche debris at 8,400,000 Glacier (fig. 17). The digitate had occurred, and both an increase m3. According to the observa- margin uf the largest avalanche in thickness and more crevassing tions of J. R. Reid (University deposit and the pt~thsfollowed were discernible in nearly all of of North Dakota) on August 1, by various parts of the debris the lower parts of the glacier. It 1965 (written commun.) , "This clearly indicate that several rock- seems likely that neither the shak- [avalanche debris] is already seen falls must have occurred from the ing nor avalanche loading is re- to be an important factor in the same general source area. No sponsible for the present advance regimen of this glacier as the marginal dust area is present. of Allen Glacier, for the advance cover has already relatively raised No dynamic eflects of the ava- was already under way prior to the surface approximately 50 feet lanches on the glacier have been the earthquake in 1964. above the bare ice adjacent to it." noted. The fact that the ice in the area where the largest 1964 FICKETT GLACIER SMALLER AVALANCHES avalanche (fig. 18) came to rest A rockslide avalanche origi- has remained almost unchanged nated on a peak at the head of the In addition to the large ava- from 1964 to 1965 suggests that small Pickett Glacier (fig. 5) and lanches described above, several there has beell no significant in- swept down the center, coming to smaller ones occurred which have crease in the amount of ice flo~v- rest in the terminal area. Al- features of interest as noted ing from this part of the glacier. though nearly 40 percent of the below. The relation of glacier regime glacier surface received some rock to earthquake effects is compli- SADDLEBAG GLACIER debris from this rockslide, the vol- cated by the fact that the Allen ume of the material was relat.ively Saddlebag Glacier (fig. 5) is Glacier has shown evidence of in- small. Some decrease in ice melt quite similar to the Sioux in size creased flow in the terminal area will probably result. and configuration. Approxi- each year since 1961. The nearby mately 50 percent of its ablation Childs Glacier, which is similar to UNNAMED GLACIER NEAR PAGUNA BAY area was covered with debris the Allen in many respects, also from many small rockslides. The clearly shows evidence of rejuve- Small rockslides from at least glacier terminates in a lake, nation and some advance in the five sources avalanched onto a which is more than 1.5 km long terminal area (figs. 19, 20). The small unnamed glacier in the Ke- and was formed largely during the retreat of the glacier since cause of the advance is unknown, nai Mountains at lat 59'42': long 1948. No appreciable change in but these glaciers probably are re- 150°03'. About 50 percent of its the glacier terminus was noted sponding normally to climatic surface was covered with rock de- between August 1963 and August fluctuations. Asbout half of the bris. Decreased melting and pos- 1965 (fig. 16). A small advance terminal area of Allen Glacier is sible future advance of this glacier or an increase in the rate of ice covered with ablation moraine and may result. ALASKA EARTHQUAKE, MARCH 27, 19 64

EXPLANATION AVALANCHE DEBRIS

Probably 1 meter or more Small volume of dust and Source area of avalanche Direction of movement thick containing rock fine rock debris fragments 3 meters or more long 1 ------)( ------Number of avalanche listed Firn line Ice-covered divide in an accompanying table

FIGURE17.-1\1al1 of rockslide avalallches on Allen Glacier. EFFECTS ON GLACIERS D23

'IBURE 18.-Alkn Glacier rockslide avalanche 1 (see fig. 17). The digitate margin of this avalanche deposit and the paths followed by variow parts of the debris, some of which override others, clearly indicate that several ra-kfalls must have occurred from the same general source area. No marginal dust layer is present. Photograph taken on August 25, 1965. - --

ALASKA EARTHQUAKE, MARCH 27, 1964

FIGURE19.-Childs Glacier, August 26, 1963, showing conditions before the earthquake; colnpam with figure 20. EFFECTS ON GLACIERS D25

E'I~URE 20.-Childs Glacier, August 23, 1963, showing conditions after the earthquake. The size and distribution of the small rockslides on the glacier are fairly typical of the slides in many areas in the Chugach and Kenai Mountains. No dynamic response of the glacier to thme avalal~cheshas been noted, nor, in view of the small volume of the rockslides, is a response probable. Since 1960, this glacier has thickened and advsl~lcerlin the terminal area. Note the change in the glacier on the right; the small marginal lakes risible in the IS63 view are almost completely covered by the advancing glacier in 1966. The Million Dollar Bridge, a span of which was shaken down by the earthquake, crosses the Copper River (lower right of the photograph). D26 ALASKA EARTHQUAKE, MARCH 2 7, 19 64

ROCKSLIDE AVALANCHES NOT ASSOCIATED WITH THE 1964 EARTHQUAKE

AVALANCHES BEFORE THE TABLE3.-Rockslide avalanche deposits on glaciers since 1946 and prior to 1964 1964 EARTHQUAKE earthquake Glacier Avalanche Large avalanches on several gla- -- ciers in Alaska occurred in the Name Area Year Latitude Longitude Area Length Direction two decades before the 1964 earth------(ha) (kmz) (km) traveled quake. Prominent older undated OlO, Casement ---______181 1945? 59 07 135 47 3 2.5 SE deposits are located on the Chisto- Johns Hopkins----_-- 310 19611 58 47 137 10 2 2 NE china Glacier in the Alaska Range Margerie -----_-_---- 130 1961 58 56 137 13 2.5 3 SE Netland _-______.._--39 19521 59 26 137 54 2.5 2.5 NW and on Casement Glacier in Gla- Smith -_---______---18 1955? 61 16 147 48 .5 1.5 E cier Bay. Rockslides have ava- Bryn Mawr ----____-_ 23 19607 61 15 147 52 1 3 ESE Vassar ----_-______--13 1958? 61 13 147 53 1 1.5 ESE lanched repeatedly on Margerie Barry ------_-__-._--78 1960 61 11 148 07 4 3.5 SE Glacier near Glacier Bay, the most Serpentine---______-_ 16 1963? 61 07 148 16 .5 2.5 W Surprise-_-______--- 57 1963 61 02 148 31 .5 1.5 SE recent in 1961. Pigot __-_-___-______21 1945? 60 54 148 29 1 3 E Some especially conspicuous alvalanches on glaciers that were noted before the 1964 earthquake probably occurred during the sum- recent smaller rock avalanches are are listed in table 3. In the mer of 1965, is the longest of any listed in table 4. These avalanches Chugach Mountains the 1960 ava- of those observed. Its overall do not differ significantly from lanche on Barry Glacier and the gradient is also much the steepest, those which occurred at the time of 1963 avalanche on Surprise in that the material was derived the earthquake. Glacier occurred about 38 and 55 from as high as 4,050 m on the 9 rockfall avalanche, more km, respectively, west of the 1964 mountain whereas the toe of the than 6 km in length, occurred on earthquake epicenter. A rockslide debris is at only 700 m (figs. 4P, Emmoils Glacier on Mount avalanche from the same source as 23). The Fairweather Glacier Rainier, WTash., in 1963 (Crandell the 1963 avalanche covered part of avalanche is 600 km east-south- and Fahnestock, 1965). No earth- the Surprise Glacier at the time of east of the 1964 earthquake but qy~akesof notable magnitude had the 1964 earthquake. near the Fairweather fault along occurred in the region between which movement occurred during 1948 and 1964, and no earthquake ROCKSLIDE AVALANCHES the 1958 earthquake. This latter was recorded at the time of the SINCE AUGUST 1964 earthquake, which registered more than 8 on the Richter Scale, caused initial rockfall. This evidence in- Two very large rockslide ava- a major rockslide avalanche into dicates that large and potentially lanches occurred in south-central Lituya Bay some 30 km south. destructive rockslide avalanches, Alaska between August 24, 1964, The location, area, and length of although more likely to occur and August 22,1965. One of these the Allen 4 and Fairweather during violent earthquakes, do (Allen Glacier 4, fig. 21) occurred Glacier avalanches as well as other occur at other times. in the vicinity of three rockslide avalanches on Allen Glacier that TABLE4.-Rockslide avalanches more recent than 1964 earthquake had probably been caused by the Glacier Avalanche 1964 earthquake. It is larger and has a lower gradient than any of Name i Area Year 1 Latitude 1 Longitude 1 (f~1 I~e&h ps- the rockslide avalanches that oc- curred at the time of the earth- Allen(avalanche4)--- 230 1965? 6047 14456 7.5 7.5 NNE quake (fig. 4E). Fairweather ------1965? 58 53 137 40 8.5 10.5 WSW B~OSSO~_- - - _ _ - _ _ _ _ - - 1965 60 03 140 05 1.5 1.5 E ,4 rockslide avalanche on Fair- 1 268 / 1 / 1 / 1 weather Glacier . (fig. 22), which EFFECTS ON GLACIERS D27

B'IGURE 21.Allen rockslide avalanche 4, \-ienT looking southweet. This avalanche was not prew~enton August 21, 1964. The soum area mas the black cliff at the head of the tributary branch of Allen Glacier. This aJalanche traveled 7.5 km and has a mnsimnm \17idth oi 1.5 knl (figs. 4E,17). Many large rock fragnents are included in the debris and a thin Payer of dirt and dast 1)orders the edge of the deposit. A much smaller avalanche, Allen 3 (table 2), which ovtcurred in 1964, can be seen to the left of the 196.7 debris. Photograph taken on August 25, 1963. - -

ALASKA EARTHQUAKE, MARCH 27, 1964 FIGURE22.-Rockslide avalanche on Fairweather Glacier August 22, 1965 ; view looking east. The avalanche scar on Mount Fairweather was not present in August 1964. Dust clouds attest to the continued fall of debris from the 5ouree area. The avalanche traveled 10.5 km and had a maximum vertical descent of 3.350 m (fig. 43'). ALASKA EARTHQUAKE, MARCH 2.7, 1964

Probably 1 meter or more Source area of avalanche Firn line Ice-covered divide thick containing rock fragments 3 meters or more long

FIGURE23.-Map of rockslide avalanche on Fairweather Glacier. EFFECTS ON GLACIERS D,31 GENERAL CHARACTERISTICS OF THE LARGER ROCKSLIDE AVALANCHES

Sherman 1, Schu-an 1, Steller contain blocks exceeding 3 in in the surrounding ice. A good ex- 1, Sioux 1, Allen 4, and the Fair- greatest dimension. The bulk of ample of such effects after several weather Glacier avalanches dis- the material consists of fairly years' ablation is a large deposit play several common character- small fragments either scattered on Netland Glacier in the Alsek istics: (a) the source area was a uniformly over the deposit or River valley which resulted from cliff currently undergoing glacial concentrated in irregular hum- a rockslide avalanche occurring erosion; (b) the volume of the mocks or windrou-s. Clearly de- some time after 1951 (fig. 24). material moved was probably at fined banding or flow lines in the W. 0. Field (written commun. least 400,000 m3; (c) the ava- direction of movement is shown 1966) states, "At the lower end lanche initially descended very by only one avalanche (fig. 6). of the Sherman slide, the debris steep slopes for at least 600 m The margins of several deposits was already on a well-formed and gained very high velocity; terminate in fairly smooth, platform on October 1, 1964, (d) on reaching the glacier, the rounded outlines (fig. 21) ; others after only one ablation season. rock debris swept over surficial are moderately irregular with In July 1965 the top of the de- features, such as medial moraines, digitate margins (5g. 6). bris at the lower end of he slide, without greatly modifying them; Smaller avalanches were highly which was about 5 feet thick, was (e) the gradient of the ava1an:he irregular (fig. 18). already about 30 feet above the on the glacier surface was often E. R. LaChapelle (written com- surrounding clear ice surface." less than 5"; (f) the distance mml., 1966) comments : Figures 11 and 21 show a con- traveled by the avalanches at low The digitate lobes exhibited by the tinuous dust layer 30 m or more gradient was several kilometers. Allen 1 and Fairweather rockslide in width around the margins of Profiles of these avalanches are avalanches [figs. 18, 223 are character- the Schwan and Allen 4 ava- shown in figure 4. istic of wet-snow avalanches. The lanches. If these avalanches 'wheeling' and erratic crossflow shown The distances traveled by the in figure 18 are often seen in large wet- traveled on cushions of com- largest Sherman, Schwan, Allen, snow avalanches which run out onto pressed air, this dust may have Steller, and Fairweather rockslide nearly level terrain. It appears that been expelled from beneath the avalanches at low gradients sug- the same flow mechanism must be at debris as the avalanche came to gest that the friction of the de- work in both wet-snow and rock ava- rest (Crandell and Fahnestock, lanches. The presence of water in bris on the glacier surface was the latter is to be suspected. Dry- 1965, p. A10). Dust bands are r e m a r k a b 1 y small. This snow avalanches do not exhibit these not present adjacent to most prompted one observer to com- peculiar flow patterns. smaller avalanche deposits, or ment that glaciers must be "slick Rockslides on glaciers resulting where the avalanche deposit has as ice." Shreve (1966) suggested from the earthquake appear to a digitate margin (Allen 1, Sher- that compressed air may have be generally composed of coarse inan 1, and Fairweather). A coilstituted an easily sheared lu- materials or are thick enough to layer of dust around the margin bricating layer for the Sherman reduce rather than increase melt- of a small rockfall on Scott Gla- avalanche. ing of the underlying ice. Thus, cier is separated from the coarse The avalanches exhibit varia- after a few years' ablation, avn- debris by 30 m or more of clean tions in the size of the fragments lanches below the firn line tend Some smaller avalanches and the density of material. to become platforms whose sur- seem to consist largely of dust Most of the larger avalanches faces stand considerably above and fine rock debris. D32 ALASKA EARTHQUAKE, MARCH 2 7, 19 64

FIGURE24.-Rockslide avalanche on NetFand Glacier (location shown on fig. 1). This avalanche occurred sometime between 1951 and 1961. Note the height of the "table," estimated to be 30 m or more, formed by the debris which has retarded the melting of the underlying ice. Photograph taken August 29, 1964. EFFECTS ON GLACIERS D33

CHANGES IN DRAINAGE AND FLOW OF GLACIALLY FED RIVERS DUE TO THEIWEARTHQUAKE

Reports that the discharge of TABLE5.-Late August levels of glacier-dammed lakes in the Chugach and Kenai Mountains, 1960-66 the Copper River was greatly re- duced temporarily after the earth- [D, drained practically dry; R,high; In, intermediate level; L, low] quake led to some speculation that Lake Glacier Lati- Longi- Length 1960 1961 1063 1964 1965 Remarks tude tude (km) changes in glaciers near the river ------might have been the cause. No 0, 0, Unnamed --....Bering ---..... 60 20 142 56 2 --.------H ....- -.... Marginal near McIntosh major changes were found in large Peak; irobably does gli~cierswhich border the river. not drain. Do------..... do ----.----17 143 01 1 ..... L ..-..--.-- -...- Near head of Kosakuts Several glaciers in the area af- River. Ha.. do 15 07 5 L L L L L InGrindleHills. Lowered to lateral fected by the earthquake block morahe about 1959 side valleys and form lakes (Stone, by glacier recession. Unnamed --....--.--do ------.-.17 16 2 L H D H ----- Marginal embayment, northwest side of 1963). Most of these lakes drain Grindle Nynatak. Dodo- 23 30 5 H H H H H In Khitrof Hills be- under or alongside the glaciers tween'Bering and Steller Glaciers' during the summer months. drains rarely if ht all. Do------.-..-. do------24 32 2 H H H ..-..H InKhitrofHilb Ragle, Sater, and Field (1965b) Steller Glacie; side; observed several of these lakes in generally ice filled. Do.. do .. 23 44 2 L --.--H L ....- Southeast of present April 1964, but, because of the Berg Lake. Berg.. do.. 25 47 8 H H H H H Formed owing to glacier recession by joining presence of snow and because of of 5 former marginal lakes. Present out- the dearth of observations made in let on bedrock. Ap- former years for comparison, they parently drains rarely fat all. firm Barkley -.--.---Tana---...... 44 142 37 2 L L L L L Formerly as much as 11 were unable to draw any con- km long in Granite C~eekvalley. Outlet clusions as to the effect of the is don margin of earthquake on these lakes. The Tana %lacier. Unnamed ------..--.do ----.----47 57 6 -.-----.-- --.-- H --.--Altitude 957 m; outlet author's photographs of many of under Tana Glacier. Do...------Unnamed -.--- 47 143 44 2 . --H L .-.-..Altitude 1250 m. be- these lakes taken in 1960, 1961, tween t&o glaiiers; ice on three sides. 1963, 1964, and 1965 provide evi- Canyon ------Martin River- 30 54 1 D --.----..- D ----- Formerly up to 3 km long; drains under dence that conditions observed in glacier. Unnf&UIed--.---....- do.-.--.--. 31 14412 2 L L L L L Sidevalley,outletover late August 1964 were typical of lateral moralne to glacier; not recently other years. med. Van Cleve-----. Miles --...... -- 42 144 22 6 H In L L L Between Miles and Van A large lake on the west side of Cleve Glaciers; probably drains Columbia Glacier (lat 61°02', long annually. Unnamed ------....-do --.--.--- 42 29 1 L ---.----.. H --.-.Lateral, probably 14T008') was considered by G. drains annually. Do.----.... McPherson --.. 35 37 2 ....------H --.--L Drainage caused wash- Swinzow to have been lowered by out of art of Copper River kighway m the earthquake (cited by Ragle 1965. Do..-..---- Unnamed -.--- 49 32 3 --.------.--Glacier blocks main and others, 1965a, p. 20). No evi- valley between two - gacie;s, West Branch dence supporting this lowering ude River. Trap-.---.-.... Tsina-- .--.-..61 14 145 55 2 ..... -.---L .---...... Between two glaciers; was found in a photograph of the probably does not .drain.. lake taken by T. L. P6w6 on April Unnamed .-....Valdez ..------13 146 07 1 H --.--.--.. H --.--Between two glaciers formerly joined. 1,1964. If recent lowering of the Iceberg..------. Tazlina ------.36 28 3 ...------.------. In side valley, east side of glacier; probably lake had taken place, snowfall drains annually. Unnamed --.--.....-do .------. 38 38 6 ----- H ...-. H ..... In side valley, west side since the earthquake had con- of glacier between glaciers. May lower cealed all evidence along the shore- annually. Do-...-.... Nelcina ...----39 52 3 -....-.--. --.-- .---- ..--- South lake of two lakes lines of any former level of the on east side of glacier. Do.. do .. 42 55 2 --.-.--.-- ---.. .--.- --..- North lake of twolakea water. on east side of glacier. Number One--- Columbia.--.- 08 48 2 H H H H H Between Columbia and The late August levels of most Anderson Glaciers. Seldom if ever drains. of the larger glacier-dammed lakes Unnamed -...... - do -.-.-.... 07 53 2 H H H H H In side valley southwest of lake Number One. in the Chugach Kenai Mountains Seldom if ever drains. Dodo.. 06 54 2 L In ---.-In D West of Clear Creek. are listed in table 5. Although Generally ice filled. D34 ALASKA EARTRQUAKE, MARCH 2 7, 1 9 64 TABLE5.-Late August levels of glacier-dammed lakes in the Chugach and Kenai data are not complete, the indica- Mountains, 1960-66-Continued

- - - tions are that 1964 conditions fol- Lati- Longi- Length 1960 1961 1963 1964 1965 Remarks lowed normal patterns and that 'lacier I tude I tude I (km) 1 I I I I 1 the 1964 earthquake had little, if any, effect on the formation and Unnamed-----_ Columbia----. 02 147 08 drainage of these lakes. I Ill Careful observations were made ByHoe -- do -- 06 12 in 1964 and 1965 to determine if ge-- ik .. 17 14835 Unnamed -.-.-.Unnamed -.--. 80 29 66 there had been changes in surficial Do-.-..---- Excelsior -.--.. 02 42 or englacial drainage systems, but no evidence of such changes was found. A few minor changes in stream channels near glaciers re- Do------I Bear ------sulting from alluvial cracking were noted. Some minor stream diversion was found where water from Sherman Glacier crossed al- luvial outwash. There was no evi- dence of any permanent changes -in stream channels. Do------Yalik ------Do---; ---.-I Petrof ------.-I

EFFECTS OF THE 1964 TECTONIC DISPLACEMENT ON GLACIERS

A subsidence ..in the central- and below the snowline of most - In several areas, glaciers flow in western Chugach and Kenai glaciers would be less than 1 per- the direction the land was tilted by Mountains as a result of the earth- cent of their total area. .Any im- the earthquake. The slopw of at quake has been reported by Plaf- mediate changes are doubtless too least 15 small glaciers (none ker (1965a, p. 1677). It would small to be detected, owing to the longer than 8 km) flowing north- appear that in almost all places the masking effect of greater varia- westward toward Nellie Juan accumulation areas of the icefields tions in the volume of snow ac- River and Kings Bay from the in these mountains were lowered cumulation and ablation resulting Sargent Icefield were increased by 1-2 m. The axis of greatest sub- from variable and unmeasured about 0.1 m per km. However, the sidence was near the crest of the climatic factors. However, im- surfaces of these glaciers slope main icefields. In the vicinity of mediate slight changes would be about 100-300 m per km, so the Cordova an uplift of nearly 2 m followed by continuing changes, percentage of increase due to the took place. The relationship of and a new surface altitude would earthquake was inconsequential. such changes to glaciers is shown be reached gradually. The total A few major glaciers flow in a on figure 25. additional change in thickness direction opposite to the way the Where the land is raised with after a long period of time for a land was tilted. The gradients of respect to the sea, the area above 15-mm net mass budget perturba- both the Chenega (Sargent Ice- the snowline on glaciers is in- field) and the lower Columbia creased and the area below the tion would be of the order of snowline is decreased. A change magnitude of 1 m (assuming a Glacier (Northern Prince William of altitude of 2 m, which is about typical ice extension rate of 1.5 Sound) -approximately 75 and 25 the maximum believed to have percent per year) according to the m per km, respectively-were taken place during the earthquake, theory proposed by Nye (1960, p. lowered by about 0.1 m per kin. would have but a tiny effect, be- 568). In all probability this Although the speed of glacier flow cause the changes in area above change could not be detected. is .sensitive to changes in slope, EFFECTS ON GLACIERS D35 D36 ALASKA EARTHQUAICE, MARCIT 27, 1964 these changes appear to be too ments appear to be due to the TABLE6.-Changes in termini of tide water glaciers in the Chugach and Ken- small to detect. Most other major lovering of these glaciers which ai Mountains, 196e66-Continued glaciers were not tilted apprecia- has allowed the sea to attack the bly, or were tilted transversely. ice more vigorously than when the Changes during- Qlacier . Small changes at the terminus glaciers ended in very shallow 1960-63 1963-65 caused by uplift or subsidence of water. the land have taken place on Wellesley ---- Minor ----- Slight glaciers that end in tidewater. advance. TABLE6.-Changes in termini of tide- Coxe ------do------Minor. Table 6 lists some of these effects. water glaciers in the Chugach and Ken- Barry------..-do------Slight The Columbia Glacier was raised ai Mountains, 1960-66 advance. Cascade------..do------Minor. about 1m and the Surprise, Harri- ["Minor" indicates small changes along the glacier Serpentine------do------100 m tennini which do not represent any appreciable man, and some other glaciers on net advanee or retreat. "Slight" indime a net retreat. change of 60 m or less over the glacier tarrmnus] Surprise-- --- 150 m Slight the western side of Prince William retreat. retreat. Hamiman--- Sound were lowered about 2 m. Changes during- Minor----- Do. Glacier Blackstone- - ---do------Minor. No changes in Columbia Glacier Beloit------do------Do. 1960-83 196a-66 Chenega ---do------Do. that can be attributed to the uplift Bainbridge- - Slight Do. are yet apparent. In areas where Columbia---- Minor ----- Minor. retreat. the land subsided, some glaciers Meares------Slight 100 .m Aialik ------Minor----- Do. advance. advance. Holgate ------do------Do. show evidence of increased tide- Yale------300m 350 m North- Slight Slight water erosion. Embayments in the retreat. retreat. western. retreat. retreat. Harvard----- Slight Slight McCarthy--- Minor ----- Minor. terminal ice cliffs of Serpentine advance. advance. Dingle- ---do------Do. and Harriman Glaciers have Smith------Minor Do. stadt. Bryn Mawr-- Slight Minor. formed since 1963. The embay- retreat.

DIRECT EFFECTS OF THE 1!%4 EARTHQUAKE ON TIDAL GLACIERS

Twelve glaciers in the Chugach are intricately crevassed. Trans- Icebergs were reported by Troy and 13 in the Kenai Mountains port of debris on the lower Colum- PQw6 (cited by Ragle and others, end in tidewater, usually at the bia Glacier, the largest tidewater 1965a, p. '7) in College Fiord on heads of steep-walled fiords. The glacier in the region, indicates that April 1, 1964, in unusual quanti- ice cliffs, rising 30 m or more above the average rate of ice movement ties. ~&rphotographs of the the wttter surface, appear highly near the center of the valley has fiord indicate that a rapid retreat, unstable, and catastrophic collapse been about 460 m per year since which has characterized Yale during the earthquake, resulting in 1960. No clear evidence of in- rapid retreat of the glacier, might Glacier in recent years, has con- have been expected. creased rate of flow of any of these tinued. This glacier is considered Photographs taken in former glaciers has been noted since the to be the main source of the float- years show that a11 these glaciers earthquake. ing ice.

INTERPRETATION OF THE DATA

EFFECT OF AVALANCHE- lanches, either through direct load- However, the order of magnitude CAUSED THICKENING ON ing or the indirect effect of pro- of these effects can be readily esti- FLOW OF GLACIERS tecting the ice from melting, have mated. For a glacier whose flow caused parts of glaciers to be thick- is entirely due to internal deforma- Most earthquake-caused snow ened by several meters. Insuffi- tion (the slip on the bed is zero), and ice avalanches on glaciers were cient data are available to cal- the surface ice velocity is propor- so small that no detectable changes culate the changes in flow velocity tional to the thickness raised to the in ice flow are to be expected. of any specific glaciers affected power (n+l), where ~nis an em- However, s o m e rockfall ava- by earthquake-related avalanches. pirical constant (Nye, 1952, p. 84). EFFECTS ON GLACIERS

Field and laboratory results in- duce an abnormal increase in ad- 1. S e v e r e earthquake shaking dicate that n equals approximately vance of the terminus of as much causes large snow and ice ava- 3. Thus, if v is velocity and h is as 10-12 m per year. lanches to fall on the upper thickness, and the slope is not However, this increase is only parts of glaciers from sur- changed the immediate increment in flow rounding mountains. rate. The termini of glaciers (re- 2. This loading upsets the dy- gions of compressing flow) are namic equilibrium of the af- If, on the other hand, the glacier generally unstable (Nye, 1960, p. fected glaciers and results in flows by slip on the bed (no inter- 563). The immediate thickening a rate of ice flow many times nal deformation), according to the might trigger an instability which ,pater than normal. only existing theory (Weertman, could continue to cause the gla- 3. The increased flow travels as a 1957, p. 38), the velocity is pro- cier to thicken and the speed to "glacier flood" which moves portional to the thickness raised increase for a number of succeed- rapidly down glacier and to the power 4/2 (n+ 1). Thus ing years. This dynamic reaction causes a sudden short-lived dv/v =2dh/h. is difficult to predict without advance of the glacier ter- knowledge of &hekinematic wave minus (Tarr and Martin, Unless some unusual and dif- properties of the particular gla- 1914, p. 18P185). ferent flow mechanism is trig- cier. Such information is avail- 4. The time delay between earth- gered, the immediate percentage able for only two small glaciers, quake and terminal advance, increase in flow velocity will be 2- neither of which is in Alaska (Nye, as the "glacier flood" travels 4 times the percentage increase in 1965). Furthermore, a layer of down glacier, is proportional glacier thickness. Thus, a glacier debris could cause an abrupt de- to the length of the glacier. 300 m thick which receives an ava- crease in ice ablation. This de- In the glaciers observed by lanche equivalent in thickness to 1 crease would result in a continuing Tarr and Martin, this delay m of ice over an appreciable part increase in thickness until a new ranged from less than 1 to of its area may be expected to in- equilibrium condition is reached. 11 years. crease its flow velocity by only 0.7- Such effects are difficult to calcu- 5. After the stresses resulting 1.3 percent. At the other extreme late, but it would not be unreason- from increased loading are a glacier only 100 m thick, on able to find an advance of 10 m in 1 dissipated, the glacier flow which is deposited an extra load year followed by an increasing abruptly returns to its nor- equivalent to 3 m of ice, might ac- rate of advance of perhaps as much mal state. celerate its flow by 6-12 percent. as 10 m per year, a tapering off This theory has since been gen- The extra load might have a to a constant slower rate of ad- erally accepted as a cause of spo- noticeable effect on the advance or vance, and then a slow decelera- radic or unusual glacier advances. retreat of certain glaciers. For a tion. It was expected that the 1964 glacier in a steady-state condition Alaska earthquake would result with a simple wedge-shaped ter- THE EARTHQUAKE- in similar avalanches and glacier minus of slope a lying on a hori- ADVANCE THEORY advances. Yet it is clear that zontal bed, the net mass budget (a) Tam and Martin (1914, p. 168- snow and ice avalanching caused at the terminus is related to the 197) reported nine glaciers which by the 1964 earthquake was in- ice velocity by a simple geometric made sudden short-lived move- significant in relation to the size of relation ments ("advances") after the ex- most glaciers and had little effect v= -a cot a tremely severe earthquakes in 1899 upon their regime. Net mass budgets at the termini near Y a k u t a t Bay, Alaska. Why did the very severe 1964 earthquake not cause more wide- of glaciers in the earthquake area Changes from near stagnation to spread snow avalanching on gla- probably are of the order of mag- rapid movement occurred in the ciers? One reason is that, as nitude of -8 m, and the slopes at decade following the earthquake. modern topographic maps show, the termini are rarely less than 10 To explain these unexpected large- few large glaciers in Ala~kahave percent. Thus, ice velocities right scale changes, Tarr and Martin areas nearby that are topographi- at the termini are generally less p r o p o s e d the Earthquake-Ad- cally suited to large-scale snow than 100 m per year. An earth- vance Theory. This theory vis- avalanching. Broad, relatively quake-induced increase in ice ualizes the following sequence of low gradient surfaces are typical velocity of 12 percent might pro- events : of the valley glaciers. The gla- D38 ALASKA EARTHQUAKE, MARCH 27, 1964 cially oversteepened cliffs of the Sixteen months after the 1964 the unconsolidated deposits on surrounding mountains retain earthquake no evidence was found which the glacier terminates. very little snow in any season, to suggest that a rapid advance Hidden Glacier advanced 3 km the greater part being removed was developing in any glacier in about 1906-07 and this advance by frequent minor avalanching the Chugach or Kenai Moun- was by far the greatest described as the snow accumulates. For tains, nor was any evidence found by Tarr and Martin. However, these reasons, snow avalanching of a "glacier flood" in transit. this glacier flows from an open rarely can have an important Because of the lack of snow and snowfield where possible sources effect on glacier regimes, regard- ice avalanching and the absence of significant avalanching are less of the violence of an earth- of any rapid advance in this re- conspicuously absent. quake. gion as a result of the 1964 earth- It is pertinent to note that the Ice avalanching on steep slopes quake rockslide avalanches, the three steep hanging glaciers on the was so minor during the 1964 Earthquake-Advance Theory was mountain west of Disenchantment earthquake as to suggest that questioned, and the data pre- Bay were not shaken down by these features are little affected sented by Tarr and Martin were the 1899 earthquake although this by earthquake shaking. Areas carefully reviewed. S e v e r a 1 area was severely shaken and the where extensive ice avalanching points can be mentioned which coastline raised 13 m. However, can occur seem relatively limited suggest that the glacier move- one of these glaciers was so un- in most glaciers. Thus, only very ments they observed may not stable that 6 years later it ava- exceptionally does it appear likely have been the result of earth- lanched into the bay when no that snow or ice avalanching on quake-induced avalanching of earthquake occurred (Tarr and glaciers could be extensive snow, ice, or rock on glaciers. Martin, 1912, p. 49). This oc- enough during any earthquake to Tarr and Martin did not ac- currence provides additional evi- add sdcient material to a gla- tually observe evidence of earth- dence that even very steeply cier to result in a rapid advance. quake-induced avalanches on the pitched glaciers are not greatly Rockslide avalanching on a few glaciers they described, except on affected by violent earthquakes. glaciers during the 1964 earth- the Galiano Glacier. Their de- On the basis of the maps then quake appeared extensive enough scriptions of the changes which available, Tarr and Mnrtin re- to upset the glaciers dynamically. took place in the Galiano Glacier ported a rough correlation be- The Martin River Glacier prob- and in alluvial deposits as much tween glacier length and the time ably received the great& loading as 8 km distant from its terminus of terminal activity following the with rockslide debris and ap- indicate that very extensive earthquake. Table 'I lists the peared to be ideally suited to test slumping must have talien place lengths of the glaciers, as meas- the Tarr and Martin theory. In along this part of the coastline ured on accurate modern maps, photographs taken in 1948, 1960, of Yakutat Bay (Tarr and and the period of terminal activ- 1961, and 1963, the upper part Martin, 1914, p. 82-86). The ity for the glaciers they observed. of the glacier where the ava- changes they noted are in some Inconsistencies are so large that lanches occurred was seen to be ways comparable to the slumping the relationship seems unlikely. extensively crevassed. Whether of alluvial deposits in the Turn- crevassing in 1964 was greater again Arm region during the GLACIER SURGES than normal could not be deter- 1964 earthquake. Alders 5-6 mined with certainty. Vertical years old, growing on the Since Tarr and Martin's work, photographs were taken of the slumped alluvium and the mo- several sudden anomalous ad- narrower parts of the lacier in raine-covered terminus of Galiano vances of glaciers have been re- 1964 and 1965 in order to deter- Glacier in 1905, indicate that the ported. Hance (1937) and Moffit mine down-valley movement of breakup of the glacier surface (1942) described the advance of ice. In the area just below the must have occurred about 1899, the Black Rapids Glacier in cen- firn line this movement amounted that is, at the time of the earth- tral Alaska. The Muldrow, to about 260 m between August quake. Tarr and Martin did not Susitna, and Yanert Glaciers at 1964 and August 1965. This report an actual advance of the various times also made similar amount is judged to be normal terminus of Galiano Glacier. The advances (Post, 1960). for a glacier of this size and changes they noted may have Aerial investigations since 1960 configuration. been caused by the slumping of in Alaska and Yukon Territory, EFFECTS ON GLACIERS

TABLE7.-Lengths and times of sudden movement of glaciers observed by Tarr and Martin tinctive medial-moraine patterns after the 1899 earthquake frequently provide evidence of [Length: As measured on accurate modern maps. Period of movement: As observed by Tarr and Martln; dabs in parentheses were not observed but were inferred] three or more former surges. Conterminous glaciers and even Period of movement Glacier Length Remarks individual branches in a single (b) Began Ended large glacier may not surge at --- the same time. Surging glaciers Galiano------8 (1899) (1900) Slumping of coast of Yakutat Bay in this area probably resulted are rare but have been reported from 1899 earthquake. Changes in many parts of the world (see, in glacier may have resulted from slumping of underlying alluvial for example, Sharp, 1954, Hat- deposits. No advance reported. tersley-Smith, 1964 ; Dolgushin Miller------5 (1899) 1901 Terminal advance, probably much less than the 1.5 km, shown by and others, 1963; Post, 1960, photographs; advance not observed. 1965, 1966). Atrevida------13 1905 1906 Rapid movement of ice in valley and into terminal lobe 8 km from The "advances" of Tarr and head of glacier; no terminal Martin seem to have been surges of advance. Haenke------14 1905 1906 Terminal advance of 1,370 m to sea the same kind described above. plus unknown movement into sea. The changes noted in the lower Hidden------19 ( 1906) (1907) Terminus advanced 3 km. Position of medial moraines indicates parts of the Lucia Glacier (Tarr steep tributaries on southwest and Martin, 1914, p. 6&69), Atre- side did not furnish more ice than normally. vida Glacier (1914, p. 69-79), and Variegated------21 1905 1906 Rapid movement of ice in valley Variegated Glacier (1914, p. 115- and terminal lobe; no terminal advance. 126) are all typical of glacier Lucia------24 ( 1908) ( 1909) Rapid movement of ice in valley surges. Even the "glacier flood" and into terminal lobe 18 km from head of glacier; no terminal that Tarr and Martin described advance. can be identified on surging gla- Nunatak------32 1909 1910 Small advance of terminus (as much as 300 m in 11 months). ciers. It is the kinematic wave A slight further advance occurred mentioned above, and can be de- in 1911 followed by retreat in 1912 of 0.4 km. tected on the surface as a zone of Marvine------48 1905 1906 Rapid movement of ice and slight intense crevassing which pro- advance of lobate part at least 40 km from head of glacier. gresses rapidly down glacier. Evidence of more than 27 gla- cier surges since 1936 has been in addition to the studies men- of 4 Inn or more may take place recorded (fig. 26). At least three tioned above, have led to the in a single year at the peak of glaciers have made two or more identification of a type of glacier the movement. The ice discharge recorded surges. The Variegated behavior, called a "surge," which may lower the surface as much Glacier surged in 1905, about can be clearly distinguished from as 150 m in the upper part of 1946, and again in 1964. The normal, climatically induced ad- the glacier. The transferred ice Kluane Glacier surged in 1941 vances (Post, 1965). A typical overrides and thrusts ahead the and 1961. Tikke Glacier surged surge is described below. formerly stagnant ice in the around 1946 and again in 1963. After a relatively long interval lower valley, and here the thick- Practically all of the observed (15-100 years) of virtual stagna- ness of the glacier often increases tion in the terminal area and as much as 60 m. The volume surging glaciers show evidence of slow increase in thickness in the of ice loss in the upper part and having made three or more upper part, the glacier is sud- gain by the lower part of the surges. denly transformed. An abrupt glacier appears to be the same. Correlation between glacier kinematic wave of ice in the up- Only rarely does the glacier ad- surges and earthquakes of Richter per glacier begins moving very vance beyond its terminal posi- magnitude 7 or greater is lacking rapidly down valley. This move- tion before the surge. Appar- (fig. 26). No glacier surges have ment results in a rapid transfer ently the active period of these been recorded in the immediate of ice from the upper regions to- surges does not exceed 34years, vicinity of any strong earthquake ward the terminus, and the sur- regardless of the size of the gla- since 1899, despite the fact that face of the glacier is chaotically cier. Such surges may occur re- many glaciers are near several of broken. A surface displacement peatedly in a single glacier; dis- the earthquake epicenters. Glacier-covered mountain region ark areas show portions of glaciers that have surged since 1936. Que- ried dates are approximate

Epicenters and magnitudes Number indicates year of occurrence

100 MILES I I I 50 100 KILOMETERS

~QUBE28-DMbuticm of observed glacier surgee since 1936 in Alaska and western Canada. EFFECTS ON GLACIERS D41

The Prince William Sound re- curred has received more earth- (fig. 26). Not one surging glacier gion of the Chugach Mountains quakes of Richter magnitude 7 or or rapid advance has been reported where the 1964 earthquake oc- greater than any area in Alaska in this area.

SUMMARY AND CONCLUSIONS

Aerial photographs show few vided an easily sheared lubricating slopes of glaciers are probably too snow and ice avalanches on gla- layer. Rockslide avalanches are small to have observable effects. ciers as a result of the 1964 earth- so extensive on the Sioux, Saddle- No evidence supporting the quake. Large and small rock- bag, and Sherman Glaciers that Earthquake-Advance Theory has slides avalanched onto glaciers at the glacier regimes have been al- been found from investigations several localities. In August 1965 tered, principally because the de- made since the 1964 Alaska earth- no clearly defined large-scale dy- bris insulates the ice and reduces quake. The nature of recent namic response to avalanche load- melting. This effect favors future surges, the lack of correlation in advances of these glaciers. ing or .other effects of earthquake time and space between them and shaking had bean found in any No apparent changes in ice- recent earthquakes, and the prob- glacier. dammed lakes or glacier drainage Large rockslide avalanches trav- resulted from the earthquake. rvbility that significant avalanch- eled several kilometers on glaciers Tidal glaciers show little imme- ing did not take place on at least at gradients of less than 5O. Two diate effects. Tectonic displace- one of the glaciers observed by of these avalanches occurred many ments affecting the altitude of gla- Tarr and Martin all render the months after the earthquake. ciers are minor when compared to Earthquake-Advance Theory sus- Compressed air may have pro- climatic influences. Changes in pect.

REFERENCES

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Sharp, R. P., 1954, Glacier flow-a re- Alaska, in September 1899: U.S. and Bering River area, south-cen- view: Geol. Soc. America Bull., v. Geol. Survey Prof. Paper 69, 135 p. tral Alaska: Geol. Soc. America, 65, no. 9, p. 821-838. Tarr, R. S., and Martin, Lawrence, 77th Ann. Mtg., Miami Beach 1964, Shreve, R. L., 1966, Air-layer lubrica- 1914, Alaskan glacier studies of Program, p. 209. tion of large avalanches Cabs.] : the National Geographic Society in Tuthill, S. J., 1966, Earthquake origin the Yakutat Bay, Prince William Geol. Soc. America Spec. Paper 87, of superglacial drift on the glaciers Sound and lower Copper River re- p. 154. gions : Washington, D.C., National of the Martin River area, south- Stone, K. H., 1963, Alaskan ice-damnied Geog. Soc., 498 p. central Alaska : Jour. Glaciology, lakes : Assoc. Am. Geographers An- Tuthill, S. J., Laird, W. M., and fieers, v. 6, no. 43, p. 83-86. nals, v. 53, no. 3, p. 332-349. T. F., 1964, Geomorphic effects of Weertman, Johannes, 1957, On the slid- Tarr, R. S., and Martin, Lawrence, 1912, the Good Friday, March 27, 1964, ing of glaciers : Jour. Glaciology, The earthquakes at Yakutat Bay, earthquake in the Martin River v. 3, no. 21, p. 33-38.