Effects on Hydrologic Regimen 

Glaciers 

r,FQLOGICA SURVFY PROFFSSIONA PAPER 544-D 
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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 transportation, communications, and utilities; and the history of the 

field investigations and reconstruction effort. 

Abstract ... 

Introduct.IQn 

Acknowledgments 

Possible effects of earthquakes 

6n glaciers. 

Snow avalaMhmg .. 

Ice avalanching 

Earthquake-intiuced roiJkslide 

avalaniJhes on glaciers 

Sherman Glacier. 

Schwan Glacier .. 

Bermg and Steller Glaciers 

Martm River Glacier. 

Sioux Glacier 

Smaller avalaniJhes . 

Saddlebag Glacier 

1. Map of sQuth-central Alaska 

2. Head of Meares Glader, 

August 24, 1964 

3. Cliffs on south side of Harvard Glacier, August 24, 

1964 ... 

4. Honzoni,al profiles of roiJkslide avalaniJhes on glaciers. . . _ . -

5. Map of rockslide avalanches 

in the Sherman and Saddlebag Glaciers area .. 

6. RQIJkshde avalantJhe on Sherman Glacier, August 25, 

1965 .• 

7. Sherman Glacier, August 26, 

1963 ________ ·-----·-

8. Sherman Glacier, August 24, 

1964. ··--

9. Map of rockslide avalanche 

on Schwan Glacier. 

Page 

D1 

1 

2 

2 

3 

5 

6 

6 

13 

13 

13 

13 

21 

21 

Page 

vi 

D4 

5 

7 

8 

9 

10 

11 

12 

CONTENTS 

Earthquake-induced rockslide 

avalaniJhes on glaciers Con 

Smaller avalantJhes TCon 

Allen Glacier_ . 

Fickett Glacier_ _ _ . 

Unnamed glacier near 

Paguna Bay 

Ro~Jkslide avalanches not associated with the 1964 earthquake. _. 

Avalanches before the 1964 

earthquake._ 

Rockshde avalaniJhes since 

August 1964 

General characteristics of the 

larger rockslide avalaniJhes .. 

ILLUSTRATIONS 

FIGURES 

10. S1Jhwan ·Glamer on August 

Pap;e 

D21 

21 

21 

26 

26 

26 

31 

Page 

26, 1963 D14 

11. Schwan Glader on August 

25, 1964___ 15 

12. Map of rockslide avalanches 

in the W axell Ridge region, 

Fering anti Steller Glaciers. . _ _ _ HI 

13. Map of roiJkslide avalaMhes 

on the Martin River an<:l 

western Steller Glaciers . _ 1 7 

14. Map of rollkslide avalanches 

and rockfalls m the Sioux, 

Johnson, and Miles Gla 

mer region 18 

11). SiQux Glacier, August 26, 

1963 and August, 24, 1964. 19 

16. Saddlebag Glacier, August 

26, 1963 anti August 25, 

1965 20 

17. Map of rockslide avalanllhes 

on Allen Glacier_ _ _ _ _ 22 

TABL~JS 

Changes m drainage and flow of 

glacially fed rivers due tQ the 

Page 

1964 earthquake D33 

Effects of the 1964 tectomc dis- . 

placement.s on glaciers 34 

Direct effects of the 1964 earihquake on titial glaciers 36 

Interpretatio11 of the data 36 

Effect of avalanche-caused 

truckemng OTJ! the flow of 

gladers 36 

The earthquake-advance 

theQry 37 

Glacier surges 38 

Summary anti conclusions 41 

References 41 

Pa!'e 

18. Allen Glamer rockslide avalanche 1, August 25, 1965. D23 

19. Crulds Gleder, August 26, 

1963.- 24 

20 Childs Glacier, August 25, 

1965.. 25 

21. Allen roiJkslide avalaMhe 4, 

August 25, 1965 27 

22. F.ockslide avalanche on Fairweather Glacier, August 

22, 1965.. 29 

23 Map of rockslide avalaniJhe 

011 Fairweather Glacier ' 30 

24 RotJkslide avalanllhll on Netland Glacier, August 29, 

1964 32 

25. Map showing relat10n of 

earthquake subsidence anti 

uplift to glaciers _ 35 

26. Observed glacier surges smre 

1936 in Alaska and western 

Canada. 40 

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 
~Bagley 

Icefields and glaciers 

138° 

0 50 100 MILES 

0 50 100 KILOMETERS 

Yakutat 

G U L F 

0 F 

ALASKA 

EXPLANATION 

Limit of cracking of alluvial deposits Epicenter of 1964 earthquake 

All enD 

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 

The 1964 Alaska earthquake occurred 

in a region where there are many 

hundreds of glaciers, large and small. 

Aerial photographic investigations indicate that no snow and ice avalanches 

of large size occurred on glaciers despite 

the violent shaking. Rockslide avalanches extended onto the glaciers in 

many localities, seven very large ones 

Alaskan glaciers are of such size 

and number that they influence the 

climate, streamflow, and works of 

man in many parts of the State. 

Their influence is especially important in the region most strongly 

affected by the Alaska earthquake 

of March 27,1964, where about 20 

percent of the land area is covered 

by ice (fig. 1). North, east, and 

west of the epicenter, the Chugach 

Mountains are covered with approximately 6,500 km2 (square 

kilometer) of icefields and snowfilled valleys from which more 

than a dozen major and hundreds 

of s m a 1 1 e r glaciers descend. 

Southwest of the epicenter the 

Sargent and Harding Icefields 

and other glaciers cover approximately 4,200 krn2 in the Kenai 

Mountains. East of the Copper 

River, the Bagley Icefield contains some 10,400 km2 of glaciers. 

By Austin Post 

ABSTRACT 

occurring in the Copper River region 

160 kilometers east of the epicenter. 

Some of these amlanches traveled several kilometers at low gradients; compressed air may have provided a lubricating layer. If long-term changes in 

glaciers due to tectonic changes in altitude and slope occur, they will probably 

be very small. No evidence of largeINTRODUCTION 

Most rivers in this area derive a 

part of their flow from glaciers, 

and, for many major streams, such 

as the Matanuska and Copper 

Rivers, glacier melt provides a 

substantial part of their summer 

runoff. Although it is primarily 

the glacial rivers that affect works 

of man in the State, in a few places 

the glaciers themselves are near 

transportation routes or facilities. 

Changes in glaciers resulting from 

earthquakes thus may have economic as well as scientific interest. 

The 1964 earthquake was one of 

the strongest ever recorded in 

North America. Tectonic displacements occurred over a larger 

area than has previously been observed (Plafker, 1965a; Plafker 

and Mayo, 1965). The area in 

which cracking occurred in alluvial deposits is considered the 

probable limit of the area where 

noticeable effects on glaciers might 

be expected (fig. 1). 

scale dynamic response of any glacier 

to earthquake shaking or avalanche 

loading was found in either the Chugach 

or Kenai Mountains 16 months after 

the 1964 earthquake, nor was there any 

evidence of surges (rapid advances) as 

postulated by the Earthquake-Advance 

Theory of !L'arr and Martin. 

The author conducted aerialphotographic investiga1;ions on 

glaciers in northwestern North 

America from 1960 to 1963 under 

grants from the National Science 

Foundation. This project was 

administered by the University of 

Washington, Seattle, P. E. Church 

being principal investigator. 

Practically all of the larger glaciers in Alaska were examined and 

their various features noted. More 

than 2,000 oblique and vertical 

photographs were taken each year. 

These observations and pictures 

provide detailed information 

about the glaciers before the earthquake occurred. 

The U.S. Geological Survey 

continued these studies in 1964 

and 1965 as part of n broader 

program of investigation of the 

relation of glaciers to climate and 

the role of glaciers in the hydrologic cycle. Mark F. Meier 

directed this program. 

Dl 
D2 ALASKA EARTHQUAKE, MARCH 27, 196:4 

By comparing photographs 

taken before and after the earthquake, the immediate effects on 

glaciers can be analyzed. The 

data available make it possible 

to determine what changes have 

occurred in other years in the 

shaken area. Changes in regions 

where earthquake shaking did not 

take place were also analyzed. 

Studies were conducted in late 

August and in September, the 

time when the seasonal snow 

cover on glacier ice is at a minimum. High-resolution aerial 

cameras were used. The following glacier features were visually examined and photographed : 

Firn line and snow cover. 

Snow, ice, and rock avalanches. 

Extent of crevassing and evidence of changes in glacier 

thickness and rate of flow. 

Surface features including 

ogives, icefalls, medial 

m o r a i n e s, superglacial 

streams and lakes. 

Glacier termini-position, 

configuration, and relative 

activity. 

Iceberg discharge of tidal 

glaciers. 

Outlet and marginal streams, 

and glacier-dammed lakes. 

Terminal and lateral morainos, trimlinw, and barren zones. 

In addition, a careful search was 

made during the 1964 and 1965 

flights to find evidence of changes 

in glaciers attributable to the 

earthquake. 

ACKNOWLEDGMENTS 

This study was made possible 

by utilizing aerial photographs 

taken for the National Science 

Foundation in 1960, 1961, and 

1963 under contract with the 

University of Washington, Seattle, Wash. Information and (or) 

photographs were furnished the 

author by George Plafker of the 

Geological Survey and Troy 

P6w6 of the University of 

Alaska, John Sater of the Arctic 

Institute of North America, and 

W. 0. Field of the American 

Geographical Society. John R. 

Reid of the University of North 

Dakota, Colin Bull of the Ohio 

State University, Institute of 

Polar Studies, Samuel Tuthill of 

Muskingum College, Ohio, furnished information regarding 

studies of Sherman and Martin 

Rivers Glaciers. Mark Meier of 

the Geological Survey discussed 

the probable effects on glaciers of 

avalanches and tectonic displacements. TV. R. Fairchild, Don 

Sheldon, and Jack Wilson provided skilled piloting on aerial 

photographic missions. D. R. 

Crandell of the Geological Survey and W. 0. Field critically 

reviewed the manuscript. 

POSSIBLE EFFECTS OF EARTHQUAKES ON GLACIERS 

Earthquakes and changes in the 

surface of the earth related to 

earthquakes can affect glaciers in 

many ways. The glaciers can be 

made thicker or thinner, the land 

surface can be so deformed as to 

cause changes in net mass budget 

(difference be tween accumulation 

and ablation of snow and ice) or 

in the slope of the glaciers, glaciers 

which calve off into water can be 

affected by shaking or by changes 

in the water body, and the glacier 

ice may be directly affected by 

shaking. Seven possible changes 

are : 

1. Increased ice thickness resulting from : 

a. Extensive avalanching of 

ice and (or) snow from 

adjacent slopes onto 

glaciers. 

b. Rockfalls and rockslide 

avalanches from adjacent slopes onto 

glaciers. 

c. Decreased melting due to 

insulation of ice provided by heavy accumulations of dust or 

rock debris on glaciers. 

d. Decreased melting due to 

increased albedo (solar 

radiation reflectivity of 

the surf ace), caused by 

accumulation of clean 

avalanche snow and ice 

over dirty ice. 

Increased ice thickness on 

glaciers results in accelerated 

glacier motion (Nye, 1952; Weertman, 195'7) and a possible advance 

of the terminus. Sudden spectacular glacier advances after the 

severe 1899 earthquake were reported by Tarr and Martin 

(1914) ; they attributed the advances to extensive earthquakeinduced avalanching of snow and 

ice onto the glaciers. Less 

spectacular effects of increased ice 

thickness might be a slowing of the 

glacier retreat, stability, or a slow 

advance of the terminus. 

2. Decreased ice thickness resulting from accelerated melting due 

to decreased albedo, caused by a 

thin surf ace layer of dust and rock 

debris. Reduced ice flow, slowing 

of advance, stagnation or retreat 

of the terminus, or even complete 
EFFECTS ON GLACIERS 

disappearance of the glacier are 

possible effects of thinning. 

3. Disruption of glacier-fed rivers 

by : 

a. Glacier advance, blocking 

the normal course of 

streams or rivers and 

forming 1 a k e s, which 

may be followed by a 

sudden release of water 

when such glacier dams 

burst or are overtopped 

and rapidly disintegrate. 

b. Closing or opening of englacial or marginal channels resulting in the impoundment or release of 

runoff. 

Highways parallel the Matanuska and Copper Rivers, and 

transportation routes follow rivers 

in the Kenai Mountains. In addition, major ports, such as Seward 

and Valdez, are near the mouths of 

glacier-fed rivers. Severe damage could result from flooding if 

The 1964 earthquake occurred at 

a time of year when large quantities of snow were present on glaciers, and avalanche hazard was 

high in some areas. E. R. LaChapelle, snow avalanche specialist with the U.S. Forest Service, 

stated (oral commun., 1966) : 

The Good Friday earthquake occurred during a period of known natural avalanche hazard in the Chugach 

Mountains in the vicinity of Anchorage 

and Turnagain Arm. The snow cover 

at this time was recorded as unstable. 

For this reason, the Forest Service 

ranger on duty at Alyeska Ski area 

closed parts of that area to public use 

a few hours prior to the earthquake. 

The subsequent occurrence of avalanches in this and other nearby areas 

indicates that the hazard prediction was 

correct. 

these streams were affected by 

earthquake-induced changes in 

glaciers. 

4. Change in flow characteristics 

of glaciers due to shaking. Sudden advances of glaciers have been 

reported where no snow and ice 

avalanching have been observed. 

The possibility that earthquake 

shaking of unstable glaciers directly results in such advances has 

been considered (Post, 1960). 

Such advances might result from: 

a. Changes within the structure of the glacier ice 

that alter its flow-law 

properties and, in consequence, the speed of internal deformation of the 

glacier. 

b. Changes in the properties 

of the boundary layer between the glacier and its 

bed that alter the rate at 

which the glacier slides. 

The author knows of no physical 

mechanism which would permit 

- -- 

SNOW AVALANCHING 

Because of the unstable snow 

conditions mentioned by LaChapelle, major avalanching onto 

the glaciers might have been expected during the earthquake. 

However, George Plafker (written commun., 1964) found little 

evidence of snow avalanches on 

the glaciers during flights made 

March 29 and April 6, 1964. He 

wrote : 

My general impression gained from 

the reconnaissance flying is that the 

volume of snow shaken down by the 

earthquake is inflnitely small relative 

to the size of the drainage basins of 

the coastal glaciers. I seriously doubt 

that the amount of snow observed in 

these avalanches could have a significant effect upon the regimen of any 

of the glaciers I saw * * *. 

shaking to cause appreciable 

changes in glacier flow rates by 

either of these phenomena. Inasmuch as no observational data on 

either mechanism are available, 

these phenomena are con~idered 

purely hypothetical and are not 

discussed further in this report. 

5. Breakup of the terminus of 

tidewater glaciers due to shaking. 

Accelerated discharge of icebergs 

and possible retreat of the glacier 

might result. 

6. Changes in lthe terminus of tidewater glaciers due to vertical 

movement of ,the land. Advance 

of raised glaciers and retreat of 

lowered glaciers are possibilities. 

7. Long-term changes in mass or 

flow characteristics of glaciers or 

both, due to change in altitude or 

slope caused by tectonic displacement. Effects may be greater or 

less, depending upon the magnitude of the changes. 

Ragle and others (1965a, p. 2) 

made reconnaissance flights between April 9-19 and September 

4-24, 1964, and summarized their 

findings as follows: 

The scarcity of obvious change was 

surprising because the glaciers must 

have been shaken violently by the earthquake. There were few snow avalanches or snow slides in the glacier 

basins and none of them appeared to 

have added enough substance to affect glacier regimen appreciably * * *. 

With a few exceptions, hanging glaciers 

did not appear to have been affected 

and there was no unusual calving of 

glacier termini into tidewater. 

Photographs taken April 1, 

1964, by T. L. P6w6 show the 

termini of Meares, Yale, Harvard, and Columbia Glaciers. No 

evidence of avalanching is shown. 
D4 ALASKA EARTHQUAKE, MARCH 27, 1964 

FIGURE 2.-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 TABLE 1.-Snow avalanches on large glaciers near the epicenter of the 1964 earthquake 

significant avalanching of ice or 

snow was found during the author's investigations in August 

1964. Traces of large winter 

or spring snow avalanches can 

usually be detected on glaciers as 

late as August because of differing snow texture, streaks of fine 

debris, or the obscuring of glacial structures. All of the larger 

glaciers in the Chugach Mountains were observed. Detailed 

oblique photographs wcre taken 

of the precipitous slopes adjacent 

to the Columbia, Meares, Yale, 

and Harvard Glaciers, all of 

which are near the epicenter (fig. 

1). The areas of these glaciers 

and the areas of earthquake-inGlacier 

Distance from epicenter Area of glacier Approximate area 1 Ikm9 1 of snow av- Direction alanches (kmz) 

duced avalanches of snow found 

on these glaciers are summarized 

in table 1. 

On the Columbia Glacier, evidence of snow avalanching was so 

minor that no more avalanches 

were noted than are shown in photographs taken in other years. A 

few small snow avalanches occurred near the head of Meares 

Glacier (fig. 2). 

Columbia- _ - - - - - - - - - - - Meares--__------..---- 

Yale----------------- 

Haward-_------------ 

Evidence of snow avalanching 

has been found each gear the 

glaciers have been examined. The 

amount of avalanching in 1964 

was not, in general, more than 

that usually detected. All observers' reports and the evidence seen 

in August 1964 indicate that 

snow avalanching resulting from 

the earthquake was not great 

enough to materially affect any 

glacier's regime. 

25 

23 

26 

35 

NE ---------------- NNE -_---------__- N----------------- 

N 

1,370 

135 

225 

505 
EFFECTS ON GLACIERS 

ICE AVALANCHING 

Large-scale avalanching of ice 

from hanging glaciers and iceveneered cliffs adjacent to large 

glaciers could materially affect a 

few glacier regimes. The glaciers 

were carefully scrutinized in 

August 1964 to determine if ice 

avalanching had taken place. 

The ice-sheathed cliffs near the 

head of Harvard Glacier are 

among the most extensive and 

steepest in the Chugach Mountains. Many small avalanches occurred on the south side of the 

glacier (fig. 3), but only two wece 

large enough to leave conspicuous 

deposits. No evidence of extensive 

ice avalanching was noted adjacent to the Yale Glacier. 

Although some steep ice on 

slopes had an unusually shattered 

appearance after the earthquake 

(Nielsen, 1965), no ice avalanches 

mere found that were large enough 

to materially affect any glacier's 

regime. 

FIGUBE 3.-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, 19 64 

EARTHQUAKE-INDUCED ROCKSLIDE AVALANCHES ON GLACIERS 

Apparently the most important 

effect of the 1964 earthquake on 

glaciers has been the change in 

their regime resulting from rockslide avalanches. Rockfalls occurred over a very broad area as a 

result of the earthquake. This 

distribution is not a simple function of distance from the epicenter, 

but is related to local structure and 

weakness in bedrock. Direction 

of avalanche movement apparently 

was controlled by local topography, no particular direction of 

movement predominating. Most 

of these rockfalls and rockslide 

avalanches were minor in both size 

and importance. 

Rockslide avalanches which occurred between August 1963 and 

August 1964 that were observed by 

the author are listed in table 2. 

The location and area of the 

glaciers and of all rockslide avalanches of more than 0.5 km2, together with the general direction 

of movement of the avalanche, are 

listed. 

Several very large rockslide avalanches occurred at the time of the 

earthquake. Profiles of these avalanches are shown on figure 4. 

Individual rockslides are described 

below. 

SHERMAN GLACIER 1 ~ust. 

TABLE 2.-Earthquake-induced rockslide avalanches 

[Slide area: more important slides in italic] 

The Sherman Glacier (figs. 4A, 

5) received one very large rockslide 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 

Glacier 

Name 

-- 

Sherman .. 

8hw 

Martin River -.--.- 

Bin .. 

Steller -.--.-....-.- 

Sioux 

on -- Unnd 

Van lee -- 81 .- 

Fickett .. 

A .. 

Scott .. 

Rude .- 

a -- C01~mb -- 

Re .. 

Set 

8 .. 

H -- PO -- Twentymile -. 

Cot .. 

Unnamed --..-.--- Do 

DO -- 

Area (kmz) 

57 -- 

1 .. 

280 ---...-------- 

5 

Branch of Bering Glacier. 

.. 

%. 

8 .- 

62 - 1 -- 

3 .. 

0 .. 

1 -- 26 ------ 

31 .. 

1,370 .. 

4 -- 

26 .- 

70 -- 

49 -- 16 -- 49 .- 

1 .. 

11 -.-.----..----- 

4 

4 - 

No. 

1 

2 

3 

4 

1 

2 

1 

2 

3 

4 

5 

6 

1 

2 

3 

4 

5 

1 

2 

3 

4 

6 

1 

2 

a -- 

-- 

-- 

-- 

- 

1 

2 

3 -- 1 

2 -- 1 

2 -- 

-- 

-- 

-- 

-- 1 

2 - 

-----. 

-- 

-- 

-- 

Latitude 

0, 

60 33 

33 

31 

32 

60 a 

57 

60 38 

36 

38 

37 

34 

33 

60 32 

30 

28 

28 

28 

60 36 

33 

33 

32 

32 

60 32 

34 

32 

60 34 

60 36 60 M 

60 31 

60 33 

60 46 

45 

47 

60 43 

60 47 

47 

61 02 

61 13 

13 

61 11 

61 09 

06 

61 02 

60 56 

60 64 

60 57 

56 

60 28 

59 48 

59 42 

59 44 

Lon i 

tud0, 

145 10 

06 

08 

10 

145 11 

08 

143 36 

38 

35 

39 

38 

44 

143 17 

10 

06 

04 

142 n 

143 17 

31 

32 

34 

39 

144 19 

18 

1s 

144 21 

144 21 

144 13 

145 06 

145 01 

144 60 

45 

55 

145 08 

145 11 

08 

145 27 

147 14 

16 

147 34 

148 16 

18 

148 31 

128 28 

148 30 

148 38 

38 

148 28 

149 57 

150 03 

1M) 15 

Avalanche 

No. 

------ 

1 

1 

1 

1 

1 

1 

1 

2 

2 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

5 

1 

4 

2 

2 

4 

1 

1 

1 

1 

3 

1 

1 

1 

1 

2 

1 

1 

1 

2 

2 

1 

1 

3 

4 

3 

2 

1 

Area rn2) 

8.6 

1.5 

1.5 

d 

i 

11.6 

6.5 

18.5 

1.5 

1 

3 

2.5 

2.5 

1 

1.5 

7.6 

1 

.5 

1 

1 

S 

1 

1 

2.5 

1.5 

1 

2.5 

1 

2 

1 

1 

1.5 

2 

1 

1.5 

1 

1 

1 

.5 

.5 

3 

1 

.5 

2 

1.5 

3 

1.5 

2.5 

.5 

Slides 

Mgth 

(km) 

6 

2.5 

3 

1.5 

6 

1.5 

3 

4 

5 

5 

3.5 

2.5 

5 

6.5 

5 

1.5 

2.5 

6.5 

2.5 

2.6 

4 

2.5 

4.5 

1 

1 

2.5 

1.5 

1 

2.5 

3 

3 

2.5 

1.5 

1 

5 

2 

2.5 

1.5 

1.5 

2 

2.5 

2 

3 

2.5 

4 

2.5 

1: 5 

1.5 

1.5 

1.5 

Direction 

traveled - 

NW. 

N. 

N. 

NE. 

NNW. 

w. 

NNW. 

NW. 

8 88E. 

8b~. 

8W. 

8. 

8. 

8. 

8. 

88E. 

N. 

N. 

8E. 

88E. 

88W. 

8. 

8. 

1NW,38W, 1 

BE. 

NW. 

1W,3NW. 

N 8E. 

N: 

188E 2 SW, 1 

NE: 

NNE. 

N. 

NW. 

N. 

8E. 

NW. 

NW. 

WNW. 

8W. 

E8E. 

8E. 

8. 

E. 

E8E. 

N. 

E. 

W. 

151W2NW. 

NE.' 

W. 

W, SW. 

E. 
EFFECTS ON GLACIERS 

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 

0 

~-s-~_·o_u_x ___ _ 

2000

1000 t:E -------------------------------------

0 ,_-----,-----,------,-----,------,-----,------.-----~ 

Allen 4 

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. 

D7 
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 

FIGURE 6.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 protected 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 

FIGURE 8.-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 looking southeast. Photograph taken August 24, 1964. 
AVALANCHE DEBRIS EXPLANATION 

Probably 1 meter or more Small volume of dust and Source area of avalanche 

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 

- 

Direction of movement 

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

25 million m3 (cubic meters) of 

shattered rock debris and minor 

amounts of admixed ice and 

snow. Practically all of this material came to rest on the glacier 

below the firn line. No marginal 

dust layer is present. Possible 

effects of the avalanches on the 

glacier include reduced ablation, 

increased flow, and advance of the 

main glacier. 

W. 0. Field of the American 

Geographical Society (written 

commun., 1966) has commented : 

"The Sherman Glacier has retreated about 800 meters previous to 1950, from forest trimlines. 

From August 5, 1950, to June 

1965, recession at the outermost 

part of the t,erminus in the middle of the valley totaled 375 

meters, representing an annual 

average of 25 meters." However, 

by late summer 1965, an advance 

of as much as 6 m in some parts 

of the terminus may have occurred (M. T. Millett, oral commun.). A push moraine about 5 

m high had formed (W. 0. Field, 

oral commun.) . Aerial photographs taken of the terminus in 

1963 and 1964 show a small retreat between those dates; little 

further change in the terminal 

position of the glacier was noted 

in 1965. 

The effect of the avalanche deposit on the behavior of the glacier 

and the mode of deposition of the 

avalanche debris are being investigated by Colin Bull of the Ohio 

State University Institute of 

Polar Studies (written commun., 

1966). 

SCHWAN GLACIER 

Although the rockslide avalanche (figs. 4B, 9) on Schwan 

Glacier is one of the largest resulting from the 1964 earthquake, 

it covers only about 15 percent of 

the ablation area of this large glacier. Its effect on the glacier's regime therefore should be relatively 

s m a 1 1. Photographs taken in 

1963, 1964, and 1965 show no apparent dynamic change in the glacier between these d& (figs.-10, 

11). 

BERING AND STELLER 

GLACIERS 

With its major branch, the Steller Glacier, the Bering Glacier 

covers an area of about 5,800 kmz. 

Pour rockslide avalanches more 

than 5 km in length and several 

smaller ones originated on Waxell 

Ridge. T h e largest avalanche 

(Steller 1) is 6.5 km in length, has 

a maximum width of 2 km, and 

probably contains at least 10 million m3 of rock. Because it lies 

well above the snowline and is 

therefore largely snow covered in 

a11 pl~otographs, few details are 

known. From a maximum source 

altitude of nearly 3,000 m, the rock 

debris descended slopes of about 

43" for 600 In. 011 reaching the 

nearly level glacier, .the material 

swept out with a gradient decreasing to less than 2" in the last 3 km 

(fig. 4C). Snow on the upper 

parts of the other rockslide avalanches on Waxell Ridge obscures 

source areas (fig. 12). Four 

small avalanches occurred on the 

western part of the Steller Glacier 

(fig. 13). 

No dynamic response to avalanche loading has been noted in 

any of the branches of Bering and 

Steller Glaciers where avalanches 

occurred. Long-term effects of 

the avalanche debris will be to reduce ice melt somewhat, but, relative to the size of these large glaciers, this effect will be insignificant. 

MARTIN RIVER GLACIER 

The Martin River Glacier (fig. 

13) is fed by three major tributaries, the most northerly of 

which received three major avalanches (Tuthill, 1966). Together 

these probably contain about 24 

million m3 of broken rock. Three 

other avdanclles on this branch 

appear to be little more than thin 

layers of dust. The avalancl~es on 

this branch of the glacier are so 

large that some dynamic response 

to the loading would seem likely. 

About 5 per.cent of the glacier surface \\-as covered with rock debris. 

As this material moves into the 

ablation area, its effect will be to 

reduce ice melt. 9 medial moraine near the center of the main 

tributary of the glacier moved 

down valley about 240 m between 

August 1964 and August 1965. 

SIOUX GLACIER 

The Sioux Glacier (unofficial 

name, Tuthill and others, 1964; 

Tuthill, 1966. Figs. 411, 14) received the greatest number of 

rockslide avalanches, for its size, 

of any valley glacier (fig. 15). 

As a result, easily detectable 

changes in the glacier's regime are 

anticipated. Long-term effects of 

the debris will be to reduce ice 

melt, which will favor rejuvenation of 'the relatively inactive 

terminal ice and may eventually 

result in advance. Various 

features of the glacier are listed 

below. 

size 

Feu ture (Rmr) 

Accumulation area --------- 12 

Area covered by debris- 2 

Ablation area -------------- 5 

Area covered by debris 

before earthquake---- 1 

Area covered by debris 

after earthquake----- 4.5 

About 17 percent of the accumulation area of the Sioux 

Glacier was covered by rockslide 

debris. Little dynamic rasponse 

to this loading could be found in 

a comparison of vertical photo- 
- 

  

ALASKA EARTHQUAKE, MARCH 27, 19 64 

~ FIGURE 10.-Schwan Glacier on August 26, 1963, s~howing conditions 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 

FIGWBE 13.-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 

FIGURE 14.-Map of rockslide avalanches in the region of Sioux, Johnson, and Miles Glaciers. 
FIGURE 15.-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 

FIGURE 16.-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 

August 1965. Some slight increase in crevassing in the area of 

the firn line may have taken place. 

After the earthqualrc, nearly 

90 percent of the ablation area 

of this glacier was covered with 

debris. Tuthill (1966) estimated 

the avalanche debris at 8,400,000 

m3. According to the observations of J. R. Reid (University 

of North Dakota) on August 1, 

1965 (written commun.) , "This 

[avalanche debris] is already seen 

to be an important factor in the 

regimen of this glacier as the 

cover has already relatively raised 

the surface approximately 50 feet 

above the bare ice adjacent to it." 

SMALLER AVALANCHES 

In addition to the large avalanches described above, several 

smaller ones occurred which have 

features of interest as noted 

below. 

SADDLEBAG GLACIER 

Saddlebag Glacier (fig. 5) is 

quite similar to the Sioux in size 

and configuration. Approximately 50 percent of its ablation 

area was covered with debris 

from many small rockslides. The 

glacier terminates in a lake, 

which is more than 1.5 km long 

and was formed largely during 

the retreat of the glacier since 

1948. No appreciable change in 

the glacier terminus was noted 

between August 1963 and August 

1965 (fig. 16). A small advance 

or an increase in the rate of ice 

discharge into the lake is likely 

because of the decreased melting 

resulting from the avalanche 

debris. 

ALLEN GLACIER 

Three rockslide avalanches 

were noted in 1964 on Allen 

Glacier (fig. 17). The digitate 

margin uf the largest avalanche 

deposit and the pt~ths followed 

by various parts of the debris 

clearly indicate that several rockfalls must have occurred from the 

same general source area. No 

marginal dust area is present. 

No dynamic eflects of the avalanches on the glacier have been 

noted. The fact that the ice in 

the area where the largest 1964 

avalanche (fig. 18) came to rest 

has remained almost unchanged 

from 1964 to 1965 suggests that 

there has beell no significant increase in the amount of ice flo~ving from this part of the glacier. 

The relation of glacier regime 

to earthquake effects is complicated by the fact that the Allen 

Glacier has shown evidence of increased flow in the terminal area 

each year since 1961. The nearby 

Childs Glacier, which is similar to 

the Allen in many respects, also 

clearly shows evidence of rejuvenation and some advance in the 

terminal area (figs. 19, 20). The 

cause of the advance is unknown, 

but these glaciers probably are responding normally to climatic 

fluctuations. Asbout half of the 

terminal area of Allen Glacier is 

covered with ablation moraine and 

has remained stagnant. The section where ice is exposed appeared 

smooth and almost inactive in 

1961 ; there were more crevasses in 

1963. The 1964 observations disclosed an advance of about 300 m 

during the previous year; in 1965 

an advance of an additional 300 m 

had occurred, and both an increase 

in thickness and more crevassing 

were discernible in nearly all of 

the lower parts of the glacier. It 

seems likely that neither the shaking nor avalanche loading is responsible for the present advance 

of Allen Glacier, for the advance 

was already under way prior to 

the earthquake in 1964. 

FICKETT GLACIER 

A rockslide avalanche originated on a peak at the head of the 

small Pickett Glacier (fig. 5) and 

swept down the center, coming to 

rest in the terminal area. Although nearly 40 percent of the 

glacier surface received some rock 

debris from this rockslide, the volume of the material was relat.ively 

small. Some decrease in ice melt 

will probably result. 

UNNAMED GLACIER NEAR 

PAGUNA BAY 

Small rockslides from at least 

five sources avalanched onto a 

small unnamed glacier in the Kenai Mountains at lat 59'42': long 

150°03'. About 50 percent of its 

surface was covered with rock debris. Decreased melting and possible future advance of this glacier 

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 

FIGURE 17.-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 

FIGURE 19.-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~ches has been noted, nor, in view of the small volume of the rockslides, is a response 

probable. Since 1960, this glacier has thickened and advsl~lcerl in 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 

1964 EARTHQUAKE 

Large avalanches on several glaciers in Alaska occurred in the 

two decades before the 1964 earthquake. Prominent older undated 

deposits are located on the Chistochina Glacier in the Alaska Range 

and on Casement Glacier in Glacier Bay. Rockslides have avalanched repeatedly on Margerie 

Glacier near Glacier Bay, the most 

recent in 1961. 

Some especially conspicuous 

alvalanches on glaciers that were 

noted before the 1964 earthquake 

are listed in table 3. In the 

Chugach Mountains the 1960 avalanche on Barry Glacier and the 

1963 avalanche on Surprise 

Glacier occurred about 38 and 55 

km, respectively, west of the 1964 

earthquake epicenter. A rockslide 

avalanche from the same source as 

the 1963 avalanche covered part of 

the Surprise Glacier at the time of 

the 1964 earthquake. 

ROCKSLIDE AVALANCHES 

SINCE AUGUST 1964 

Two very large rockslide avalanches occurred in south-central 

Alaska between August 24, 1964, 

and August 22,1965. One of these 

(Allen Glacier 4, fig. 21) occurred 

in the vicinity of three rockslide 

avalanches on Allen Glacier that 

had probably been caused by the 

1964 earthquake. It is larger and 

has a lower gradient than any of 

the rockslide avalanches that occurred at the time of the earthquake (fig. 4E). 

,4 rockslide avalanche on Fairweather Glacier . (fig. 22), which 

TABLE 3.-Rockslide avalanche deposits on glaciers since 1946 and prior to 1964 

earthquake 

probably occurred during the summer of 1965, is the longest of any 

of those observed. Its overall 

gradient is also much the steepest, 

in that the material was derived 

from as high as 4,050 m on the 

mountain whereas the toe of the 

debris is at only 700 m (figs. 4P, 

23). The Fairweather Glacier 

avalanche is 600 km east-southeast of the 1964 earthquake but 

near the Fairweather fault along 

which movement occurred during 

the 1958 earthquake. This latter 

earthquake, which registered more 

than 8 on the Richter Scale, caused 

a major rockslide avalanche into 

Lituya Bay some 30 km south. 

The location, area, and length of 

the Allen 4 and Fairweather 

recent smaller rock avalanches are 

listed in table 4. These avalanches 

do not differ significantly from 

those which occurred at the time of 

the earthquake. 

9 rockfall avalanche, more 

than 6 km in length, occurred on 

Emmoils Glacier on Mount 

Rainier, WTash., in 1963 (Crandell 

and Fahnestock, 1965). No earthqy~akes of notable magnitude had 

occurred in the region between 

1948 and 1964, and no earthquake 

was recorded at the time of the 

initial rockfall. This evidence indicates that large and potentially 

destructive rockslide avalanches, 

although more likely to occur 

during violent earthquakes, do 

Glacier 

Glacier avalanches as well as other occur at other times. 

Name 

Casement ---________ Johns Hopkins----_-- 

Margerie -----_-_---- 

Netland _-______.._-- 

Smith -_---_______--- Bryn Mawr ----____-_ Vassar ----_-______-- Barry ------_-__-._-- 

Serpentine ---______-_ Surprise -_-_______--- Pigot __-_-___-______ 

Avalanche 

TABLE 4.-Rockslide avalanches more recent than 1964 earthquake 

Area 

(ha) 

181 

310 

130 

39 

18 

23 

13 

78 

16 

57 

21 

-- 

Year 

1945? 

19611 

1961 

19521 

1955? 

19607 

1958? 

1960 

1963? 

1963 

1945? 

Allen(avalanche4)--- 230 1965? 6047 14456 7.5 7.5 NNE 

Fairweather - - - - - - - - - 1965? 58 53 137 40 8.5 10.5 WSW 

B~OSSO~_ - - - _ _ - _ _ _ _ - - 1 268 / 1965 1 60 03 / 140 05 1 1.5 / 1.5 1 E 

Length 

(km) 

2.5 

2 

3 

2.5 

1.5 

3 

1.5 

3.5 

2.5 

1.5 

3 

Glacier 

Name Area i 

Latitude 

------ 

59 07 

58 47 

58 56 

59 26 

61 16 

61 15 

61 13 

61 11 

61 07 

61 02 

60 54 

Direction 

traveled 

SE 

NE 

SE 

NW 

E 

ESE 

ESE 

SE 

W 

SE 

E 

Avalanche 

Year 1 Latitude 1 Longitude 1 (f~ 1 I~e&h psLongitude 

OlO, 

135 47 

137 10 

137 13 

137 54 

147 48 

147 52 

147 53 

148 07 

148 16 

148 31 

148 29 

Area 

(kmz) 

3 

2 

2.5 

2.5 

.5 

1 

1 

4 

.5 

.5 

1 
EFFECTS ON GLACIERS D27 

B'IGURE 21.Allen rockslide avalanche 4, \-ienT looking southweet. This avalanche was not prew~ent on 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. 

FIGURE 22.-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, 19 64 

Probably 1 meter or more Source area of avalanche Firn line Ice-covered divide 

thick containing rock 

fragments 3 meters or 

more long 

FIGURE 23.-Map of rockslide avalanche on Fairweather Glacier. 
EFFECTS ON GLACIERS D,3 1 

GENERAL CHARACTERISTICS OF THE LARGER ROCKSLIDE AVALANCHES 

Sherman 1, Schu-an 1, Steller 

1, Sioux 1, Allen 4, and the Fairweather Glacier avalanches display several common characteristics: (a) the source area was a 

cliff currently undergoing glacial 

erosion; (b) the volume of the 

material moved was probably at 

least 400,000 m3; (c) the avalanche initially descended very 

steep slopes for at least 600 m 

and gained very high velocity; 

(d) on reaching the glacier, the 

rock debris swept over surficial 

features, such as medial moraines, 

without greatly modifying them; 

(e) the gradient of the ava1an:he 

on the glacier surface was often 

less than 5"; (f) the distance 

traveled by the avalanches at low 

gradient was several kilometers. 

Profiles of these avalanches are 

shown in figure 4. 

The distances traveled by the 

largest Sherman, Schwan, Allen, 

Steller, and Fairweather rockslide 

avalanches at low gradients suggest that the friction of the debris on the glacier surface was 

r e m a r k a b 1 y small. This 

prompted one observer to comment that glaciers must be "slick 

as ice." Shreve (1966) suggested 

that compressed air may have 

coilstituted an easily sheared lubricating layer for the Sherman 

avalanche. 

The avalanches exhibit variations in the size of the fragments 

and the density of material. 

Most of the larger avalanches 

contain blocks exceeding 3 in in 

greatest dimension. The bulk of 

the material consists of fairly 

small fragments either scattered 

uniformly over the deposit or 

concentrated in irregular hummocks or windrou-s. Clearly defined banding or flow lines in the 

direction of movement is shown 

by only one avalanche (fig. 6). 

The margins of several deposits 

terminate in fairly smooth, 

rounded outlines (fig. 21) ; others 

are moderately irregular with 

digitate margins (5g. 6). 

Smaller avalanches were highly 

irregular (fig. 18). 

E. R. LaChapelle (written commml., 1966) comments : 

The digitate lobes exhibited by the 

Allen 1 and Fairweather rockslide 

avalanches [figs. 18, 223 are characteristic of wet-snow avalanches. The 

'wheeling' and erratic crossflow shown 

in figure 18 are often seen in large wetsnow avalanches which run out onto 

nearly level terrain. It appears that 

the same flow mechanism must be at 

work in both wet-snow and rock avalanches. The presence of water in 

the latter is to be suspected. Drysnow avalanches do not exhibit these 

peculiar flow patterns. 

Rockslides on glaciers resulting 

from the earthquake appear to 

be generally composed of coarse 

materials or are thick enough to 

reduce rather than increase melting of the underlying ice. Thus, 

after a few years' ablation, avnlanches below the firn line tend 

to become platforms whose surfaces stand considerably above 

the surrounding ice. A good example of such effects after several 

years' ablation is a large deposit 

on Netland Glacier in the Alsek 

River valley which resulted from 

a rockslide avalanche occurring 

some time after 1951 (fig. 24). 

W. 0. Field (written commun. 

1966) states, "At the lower end 

of the Sherman slide, the debris 

was already on a well-formed 

platform on October 1, 1964, 

after only one ablation season. 

In July 1965 the top of the debris at the lower end of he slide, 

which was about 5 feet thick, was 

already about 30 feet above the 

surrounding clear ice surface." 

Figures 11 and 21 show a continuous dust layer 30 m or more 

in width around the margins of 

the Schwan and Allen 4 avalanches. If these avalanches 

traveled on cushions of compressed air, this dust may have 

been expelled from beneath the 

debris as the avalanche came to 

rest (Crandell and Fahnestock, 

1965, p. A10). Dust bands are 

not present adjacent to most 

smaller avalanche deposits, or 

where the avalanche deposit has 

a digitate margin (Allen 1, Sherinan 1, and Fairweather). A 

layer of dust around the margin 

of a small rockfall on Scott Glacier is separated from the coarse 

debris by 30 m or more of clean 

Some smaller avalanches 

seem to consist largely of dust 

and fine rock debris. 
D32 ALASKA EARTHQUAKE, MARCH 2 7, 19 64 

FIGURE 24.-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 TABLE 5.-Late August levels of glacier-dammed lakes in the Chugach and Kenai 

Mountains, 1960-66 

In, intermediate level; L, low] 

1960 

- 

--.-- 

..... 

L 

L 

H 

H 

L 

H 

L 

-.--- 

. 

D 

L 

H 

L 

....- 

--.-- 

..... 

H 

...-- 

----- 

-.... 

--.-. 

H 

H 

L 

practically dry; R, high; 

the Copper River was greatly reduced temporarily after the earthquake led to some speculation that 

changes in glaciers near the river 

might have been the cause. No 

major changes were found in large 

gli~ciers which border the river. 

Several glaciers in the area affected by the earthquake block 

side valleys and form lakes (Stone, 

1963). Most of these lakes drain 

under or alongside the glaciers 

during the summer months. 

Ragle, Sater, and Field (1965b) 

observed several of these lakes in 

April 1964, but, because of the 

presence of snow and because of 

the dearth of observations made in 

former years for comparison, they 

were unable to draw any firm conclusions as to the effect of the 

earthquake on these lakes. The 

author's photographs of many of 

these lakes taken in 1960, 1961, 

1963, 1964, and 1965 provide evidence that conditions observed in 

late August 1964 were typical of 

other years. 

A large lake on the west side of 

Columbia Glacier (lat 61°02', long 

14T008') was considered by G. 

Swinzow to have been lowered by 

the earthquake (cited by Ragle 

and others, 1965a, p. 20). - No evidence supporting this lowering 

was found in a photograph of the 

lake taken by T. L. P6w6 on April 

1,1964. If recent lowering of the 

lake had taken place, snowfall 

since the earthquake had concealed all evidence along the shorelines of any former level of the 

water. 

The late August levels of most 

of the larger glacier-dammed lakes 

in the Chugach Kenai Mountains 

are listed in table 5. Although 

Lake 

Unnamed --.... 

Do --------- 

Ha .. 

Unnamed --.... 

Do 

Do --------.-..-. 

Do .. 

Berg .. 

Barkley -.--.--- 

Unnamed ------ 

Do ...------ 

Canyon -------- 

Unnf&UIed --.---....- 

Van Cleve -----. 

Unnamed ------ 

Do .----.... 

Do ..-..---- 

Trap -.---.-.... 

Unnamed .-.... 

Iceberg ..------. 

Unnamed --.--. 

Do -...-.... 

Do .. 

Number One--- 

Unnamed -..... 

Do 

Lati- 

- 

tude 

0, 

60 20 

17 

15 

17 

23 

24 

23 

25 

44 

47 

47 

30 

31 

42 

42 

35 

49 

61 14 

13 

36 

38 

39 

42 

08 

07 

06 

[D, drained 

Glacier 

Bering ---..... 

..... do ----.---- 

do 

--.--do ------.-. 

do - 

do --------- 

do .. 

do .. 

Tana ---....... 

..--.do ----.---- 

Unnamed -.--- 

Martin Riverdo .-.--.--. 

Miles --......-- 

....- do --.--.--- 

McPherson --.. 

Unnamed -.--- 

Tsina-- .--.-.. 

Valdez ..------ 

Tazlina ------. 

....- do .-------. 

Nelcina ...---- 

do .. 

Columbia.--.- 

....- do -.-.-.... 

do .. 

1961 

- 

----- 

L 

L 

H 

H 

H 

--.-- 

H 

L 

--.-- 

-- 

--.-- 

L 

In 

---.- 

----- 

----- 

-.--- 

--.-- 

----- 

H 

-.--. 

--.-- 

H 

H 

In 

Longi- 

- 

tude 

0, 

142 56 

143 01 

07 

16 

30 

32 

44 

47 

142 37 

57 

143 44 

54 

14412 

144 22 

29 

37 

32 

145 55 

146 07 

28 

38 

52 

55 

48 

53 

54 

Length 

- 

(km) 

2 

1 

5 

2 

5 

2 

2 

8 

2 

6 

2 

1 

2 

6 

1 

2 

3 

2 

1 

3 

6 

3 

2 

2 

2 

2 

1063 

- 

H 

..-.. 

L 

D 

H 

H 

H 

H 

L 

--.-- 

H 

--..- 

L 

L 

---.. 

H 

----- 

L 

.--.. 

----- 

...-. 

--.-- 

---.. 

H 

H 

---.- 

Remarks 

Marginal near McIntosh 

Peak; irobably does not drain. 

Near head of Kosakuts 

River. 

InGrindleHills. 

Lowered to lateral 

morahe about 1959 

by glacier recession. Marginal embayment, northwest side of 

Grindle Nynatak. In Khitrof Hills between'Bering and 

Steller Glaciers' 

drains rarely if ht all. 

InKhitrofHilb 

Steller Glacie; side; generally ice filled. 

Southeast of present 

Berg Lake. 

Formed owing to glacier recession by joining of 5 former marginal lakes. Present out- let on bedrock. Ap- parently drains rarely fat all. 

Formerly as much as 11 

km long in Granite 

C~eek valley. Outlet 

is don margin of 

Tana %lacier. 

Altitude 957 m; outlet 

under Tana Glacier. 

Altitude 1250 m. be- tween t&o glaiiers; ice on three sides. 

Formerly up to 3 km 

long; drains under 

glacier. 

Sidevalley,outletover 

lateral moralne to glacier; not recently med. 

Between Miles and Van 

Cleve Glaciers; 

probably drains 

annually. 

Lateral, probably 

drains annually. 

Drainage caused wash- out of art of Copper River kighway m 1965. 

Glacier blocks main 

valley between two 

gacie;s, West Branch 

ude River. 

Between two glaciers; 

probably does not .drain.. 

Between two glaciers formerly joined. In side valley, east side 

of glacier; probably drains annually. 

In side valley, west side 

of glacier between glaciers. May lower 

annually. 

South lake of two lakes on east side of glacier. North lake of twolakea on east side of glacier. Between Columbia and 

Anderson Glaciers. 

Seldom if ever drains. 

In side valley southwest 

of lake Number One. 

Seldom if ever drains. 

West of Clear Creek. 

Generally ice filled. 

1964 

- 

....- 

--.-- 

L 

H 

H 

..-.. 

L 

H 

L 

H 

L 

D 

L 

L 

H 

--.-- 

----- 

.---. 

H 

--.-- 

H 

.---- 

.--.- 

H 

H 

In 

1965 

- 

-.... 

-...- 

L 

----- 

H 

H 

....- 

H 

L 

--.-- 

.-.-.. 

----- 

L 

L 

--.-. 

L 

--.-- 

..... 

--.-- 

----. 

..... 

..--- 

--..- 

H 

H 

D 
D34 ALASKA EARTRQUAKE, MARCH 2 7, 1 9 64 

TABLE 5.-Late August levels of glacier-dammed lakes in the Chugach and Kenai 

Mountains, 1960-66-Continued - - - 

Lati- Longi- Length 1960 1961 1963 1964 1965 

'lacier I tude I tude I (km) 1 I I I I 1 Remarks 

Unnamed -----_ Columbia ----. 02 147 08 I Ill 

By Hoe -- do -- 06 12 

ge -- ik .. 17 14835 

Unnamed -.-.-. Unnamed -.--. 80 29 66 

Do -.-..---- Excelsior -.--.. 02 42 

Do --------- I Bear ---------- 

Do --------- Yalik --------- 

Do---; ---.- Petrof -------.- I I 

data are not complete, the indications are that 1964 conditions followed normal patterns and that 

the 1964 earthquake had little, if 

any, effect on the formation and 

drainage of these lakes. 

Careful observations were made 

in 1964 and 1965 to determine if 

there had been changes in surficial 

or englacial drainage systems, but 

no evidence of such changes was 

found. A few minor changes in 

stream channels near glaciers resulting from alluvial cracking 

were noted. Some minor stream 

diversion was found where water 

from Sherman Glacier crossed alluvial outwash. There was no evidence of any permanent changes 

-in stream channels. 

EFFECTS OF THE 1964 TECTONIC DISPLACEMENT ON GLACIERS 

A subsidence ..in the centralwestern Chugach and Kenai 

Mountains as a result of the earthquake has been reported by Plafker (1965a, p. 1677). It would 

appear that in almost all places the 

accumulation areas of the icefields 

in these mountains were lowered 

1-2 m. The axis of greatest subsidence was near the crest of the 

main icefields. In the vicinity of 

Cordova an uplift of nearly 2 m 

took place. The relationship of 

such changes to glaciers is shown 

on figure 25. 

Where the land is raised with 

respect to the sea, the area above 

the snowline on glaciers is increased and the area below the 

snowline is decreased. A change 

of altitude of 2 m, which is about 

the maximum believed to have 

taken place during the earthquake, 

would have but a tiny effect, because the changes in area above 

and below the snowline of most 

glaciers would be less than 1 percent of their total area. .Any immediate changes are doubtless too 

small to be detected, owing to the 

masking effect of greater variations in the volume of snow accumulation and ablation resulting 

from variable and unmeasured 

climatic factors. However, immediate slight changes would be 

followed by continuing changes, 

and a new surface altitude would 

be reached gradually. The total 

additional change in thickness 

after a long period of time for a 

15-mm net mass budget perturbation would be of the order of 

magnitude of 1 m (assuming a 

typical ice extension rate of 1.5 

percent per year) according to the 

theory proposed by Nye (1960, p. 

568). In all probability this 

change could not be detected. 

- In several areas, glaciers flow in 

the direction the land was tilted by 

the earthquake. The slopw of at 

least 15 small glaciers (none 

longer than 8 km) flowing northwestward toward Nellie Juan 

River and Kings Bay from the 

Sargent Icefield were increased by 

about 0.1 m per km. However, the 

surfaces of these glaciers slope 

about 100-300 m per km, so the 

percentage of increase due to the 

earthquake was inconsequential. 

A few major glaciers flow in a 

direction opposite to the way the 

land was tilted. The gradients of 

both the Chenega (Sargent Icefield) and the lower Columbia 

Glacier (Northern Prince William 

Sound) -approximately 75 and 25 

m per km, respectively-were 

lowered by about 0.1 m per kin. 

Although the speed of glacier flow 

is .sensitive to changes in slope, 

D36 ALASKA EARTHQUAICE, MARCIT 27, 1964 

these changes appear to be too 

small to detect. Most other major 

glaciers were not tilted appreciably, or were tilted transversely. 

Small changes at the terminus 

caused by uplift or subsidence of 

the land have taken place on 

glaciers that end in tidewater. 

Table 6 lists some of these effects. 

The Columbia Glacier was raised 

about 1 m and the Surprise, Harriman, and some other glaciers on 

the western side of Prince William 

Sound were lowered about 2 m. 

No changes in Columbia Glacier 

that can be attributed to the uplift 

are yet apparent. In areas where 

the land subsided, some glaciers 

show evidence of increased tidewater erosion. Embayments in the 

terminal ice cliffs of Serpentine 

and Harriman Glaciers have 

formed since 1963. The embayments appear to be due to the TABLE 6.-Changes in termini of tide 

lovering of these glaciers which water glaciers in the Chugach and Ken- ai Mountains, 196e66-Continued 

has allowed the sea to attack the 

ice more vigorously than when the 

glaciers ended in very shallow 

water. 

TABLE 6.-Changes in termini of tidewater glaciers in the Chugach and Kenai Mountains, 1960-66 

["Minor" indicates small changes along the glacier tennini which do not represent any appreciable net advanee or retreat. "Slight" indime a net 

change of 60 m or less over the glacier tarrmnus] 

Glacier 

Columbia ---- Meares---- - - 

Yale-------- 

Harvard----- 

Smith ------- Bryn Mawr-- 

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

Qlacier . 

Wellesley ---- 

Coxe -------- Barry-- - --- - 

Cascade- - - - - Serpentine--- 

Surprise-- --- 

Hamiman--- 

Blackstone- - Beloit ------- Chenega 

Bainbridge- - 

Aialik ------- Holgate ----- Northwestern. 

McCarthy--- 

Dinglestadt. 

Twelve glaciers in the Chugach 

and 13 in the Kenai Mountains 

end in tidewater, usually at the 

heads of steep-walled fiords. The 

ice cliffs, rising 30 m or more above 

the wttter surface, appear highly 

unstable, and catastrophic collapse 

during the earthquake, resulting in 

rapid retreat of the glacier, might 

have been expected. 

Photographs taken in former 

years show that a11 these glaciers 

Changes duringare intricately crevassed. Transport of debris on the lower Columbia Glacier, the largest tidewater 

glacier in the region, indicates that 

the average rate of ice movement 

near the center of the valley has 

been about 460 m per year since 

1960. No clear evidence of increased rate of flow of any of these 

glaciers has been noted since the 

earthquake. 

Changes during1960-83 

Minor ----- Slight 

advance. 

300m 

retreat. 

Slight advance. 

Minor 

Slight 

retreat. 

Icebergs were reported by Troy 

PQw6 (cited by Ragle and others, 

1965a, p. '7) in College Fiord on 

April 1, 1964, in unusual quantities. ~&r photographs of the 

fiord indicate that a rapid retreat, 

which has characterized Yale 

Glacier in recent years, has continued. This glacier is considered 

to be the main source of the floating ice. 

1960-63 

Minor ----- 

---do ------ - ..-do-- - - -- 

--..do- - - - - - - - -do-- - - - - 

150 m retreat. 

Minor ----- ---do- - - - - - ---do ------ ---do ------ Slight 

retreat. 

Minor ----- ---do ------ Slight 

retreat. 

Minor ----- ---do ------ 

196a-66 

Minor. 

100 .m 

advance. 

350 m 

retreat. 

Slight 

advance. 

Do. 

Minor. 

INTERPRETATION OF THE DATA 

1963-65 

Slight 

advance. 

Minor. 

Slight 

advance. 

Minor. 

100 m retreat. 

Slight 

retreat. 

Do. 

Minor. 

Do. 

Do. 

Do. 

Do. 

Do. 

Slight 

retreat. 

Minor. 

Do. 

EFFECT OF AVALANCHECAUSED THICKENING ON 

FLOW OF GLACIERS 

Most earthquake-caused snow 

and ice avalanches on glaciers were 

so small that no detectable changes 

in ice flow are to be expected. 

However, s o m e rockfall avalanches, either through direct loading or the indirect effect of protecting the ice from melting, have 

caused parts of glaciers to be thickened by several meters. Insufficient data are available to calculate the changes in flow velocity 

of any specific glaciers affected 

by earthquake-related avalanches. 

However, the order of magnitude 

of these effects can be readily estimated. For a glacier whose flow 

is entirely due to internal deformation (the slip on the bed is zero), 

the surface ice velocity is proportional to the thickness raised to the 

power (n+l), where ~n is an empirical constant (Nye, 1952, p. 84). 
EFFECTS ON GLACIERS 

Field and laboratory results indicate that n equals approximately 

3. Thus, if v is velocity and h is 

thickness, and the slope is not 

changed 

If, on the other hand, the glacier 

flows by slip on the bed (no internal deformation), according to the 

only existing theory (Weertman, 

1957, p. 38), the velocity is proportional to the thickness raised 

to the power 4/2 (n+ 1). Thus 

dv/v =2dh/h. 

Unless some unusual and different flow mechanism is triggered, the immediate percentage 

increase in flow velocity will be 2- 

4 times the percentage increase in 

glacier thickness. Thus, a glacier 

300 m thick which receives an avalanche equivalent in thickness to 1 

m of ice over an appreciable part 

of its area may be expected to increase its flow velocity by only 0.7- 

1.3 percent. At the other extreme 

a glacier only 100 m thick, on 

which is deposited an extra load 

equivalent to 3 m of ice, might accelerate its flow by 6-12 percent. 

The extra load might have a 

noticeable effect on the advance or 

retreat of certain glaciers. For a 

glacier in a steady-state condition 

with a simple wedge-shaped terminus of slope a lying on a horizontal bed, the net mass budget (a) 

at the terminus is related to the 

ice velocity by a simple geometric 

relation 

v= -a cot a 

Net mass budgets at the termini 

of glaciers in the earthquake area 

probably are of the order of magnitude of -8 m, and the slopes at 

the termini are rarely less than 10 

percent. Thus, ice velocities right 

at the termini are generally less 

than 100 m per year. An earthquake-induced increase in ice 

velocity of 12 percent might produce an abnormal increase in advance of the terminus of as much 

as 10-12 m per year. 

However, this increase is only 

the immediate increment in flow 

rate. The termini of glaciers (regions of compressing flow) are 

generally unstable (Nye, 1960, p. 

563). The immediate thickening 

might trigger an instability which 

could continue to cause the glacier to thicken and the speed to 

increase for a number of succeeding years. This dynamic reaction 

is difficult to predict without 

knowledge of &he kinematic wave 

properties of the particular glacier. Such information is available for only two small glaciers, 

neither of which is in Alaska (Nye, 

1965). Furthermore, a layer of 

debris could cause an abrupt decrease in ice ablation. This decrease would result in a continuing 

increase in thickness until a new 

equilibrium condition is reached. 

Such effects are difficult to calculate, but it would not be unreasonable to find an advance of 10 m in 1 

year followed by an increasing 

rate of advance of perhaps as much 

as 10 m per year, a tapering off 

to a constant slower rate of advance, and then a slow deceleration. 

THE EARTHQUAKEADVANCE THEORY 

Tam and Martin (1914, p. 168- 

197) reported nine glaciers which 

made sudden short-lived movements ("advances") after the extremely severe earthquakes in 1899 

near Y a k u t a t Bay, Alaska. 

Changes from near stagnation to 

rapid movement occurred in the 

decade following the earthquake. 

To explain these unexpected largescale changes, Tarr and Martin 

p r o p o s e d the Earthquake-Advance Theory. This theory visualizes the following sequence of 

events : 

1. S e v e r e earthquake shaking 

causes large snow and ice avalanches to fall on the upper 

parts of glaciers from surrounding mountains. 

2. This loading upsets the dynamic equilibrium of the affected glaciers and results in 

a rate of ice flow many times 

,pater than normal. 

3. The increased flow travels as a 

"glacier flood" which moves 

rapidly down glacier and 

causes a sudden short-lived 

advance of the glacier terminus (Tarr and Martin, 

1914, p. 18P185). 

4. The time delay between earthquake and terminal advance, 

as the "glacier flood" travels 

down glacier, is proportional 

to the length of the glacier. 

In the glaciers observed by 

Tarr and Martin, this delay 

ranged from less than 1 to 

11 years. 

5. After the stresses resulting 

from increased loading are 

dissipated, the glacier flow 

abruptly returns to its normal state. 

This theory has since been generally accepted as a cause of sporadic or unusual glacier advances. 

It was expected that the 1964 

Alaska earthquake would result 

in similar avalanches and glacier 

advances. Yet it is clear that 

snow and ice avalanching caused 

by the 1964 earthquake was insignificant in relation to the size of 

most glaciers and had little effect 

upon their regime. 

Why did the very severe 1964 

earthquake not cause more widespread snow avalanching on glaciers? One reason is that, as 

modern topographic maps show, 

few large glaciers in Ala~ka have 

areas nearby that are topographically suited to large-scale snow 

avalanching. Broad, relatively 

low gradient surfaces are typical 

of the valley glaciers. The gla- 
D38 ALASKA EARTHQUAKE, MARCH 27, 1964 

cially oversteepened cliffs of the 

surrounding mountains retain 

very little snow in any season, 

the greater part being removed 

by frequent minor avalanching 

as the snow accumulates. For 

these reasons, snow avalanching 

rarely can have an important 

effect on glacier regimes, regardless of the violence of an earthquake. 

Ice avalanching on steep slopes 

was so minor during the 1964 

earthquake as to suggest that 

these features are little affected 

by earthquake shaking. Areas 

where extensive ice avalanching 

can occur seem relatively limited 

in most glaciers. Thus, only very 

exceptionally does it appear likely 

that snow or ice avalanching on 

glaciers could be extensive 

enough during any earthquake to 

add sdcient material to a glacier to result in a rapid advance. 

Rockslide avalanching on a few 

glaciers during the 1964 earthquake appeared extensive enough 

to upset the glaciers dynamically. 

The Martin River Glacier probably received the great& loading 

with rockslide debris and appeared to be ideally suited to test 

the Tarr and Martin theory. In 

photographs taken in 1948, 1960, 

1961, and 1963, the upper part 

of the glacier where the avalanches occurred was seen to be 

extensively crevassed. Whether 

crevassing in 1964 was greater 

than normal could not be determined with certainty. Vertical 

photographs were taken of the 

narrower parts of the lacier in 

1964 and 1965 in order to determine down-valley movement of 

ice. In the area just below the 

firn line this movement amounted 

to about 260 m between August 

1964 and August 1965. This 

amount is judged to be normal 

for a glacier of this size and 

configuration. 

Sixteen months after the 1964 

earthquake no evidence was found 

to suggest that a rapid advance 

was developing in any glacier in 

the Chugach or Kenai Mountains, nor was any evidence found 

of a "glacier flood" in transit. 

Because of the lack of snow and 

ice avalanching and the absence 

of any rapid advance in this region as a result of the 1964 earthquake rockslide avalanches, the 

Earthquake-Advance Theory was 

questioned, and the data presented by Tarr and Martin were 

carefully reviewed. S e v e r a 1 

points can be mentioned which 

suggest that the glacier movements they observed may not 

have been the result of earthquake-induced avalanching of 

snow, ice, or rock on glaciers. 

Tarr and Martin did not actually observe evidence of earthquake-induced avalanches on the 

glaciers they described, except on 

the Galiano Glacier. Their descriptions of the changes which 

took place in the Galiano Glacier 

and in alluvial deposits as much 

as 8 km distant from its terminus 

indicate that very extensive 

slumping must have talien place 

along this part of the coastline 

of Yakutat Bay (Tarr and 

Martin, 1914, p. 82-86). The 

changes they noted are in some 

ways comparable to the slumping 

of alluvial deposits in the Turnagain Arm region during the 

1964 earthquake. Alders 5-6 

years old, growing on the 

slumped alluvium and the moraine-covered terminus of Galiano 

Glacier in 1905, indicate that the 

breakup of the glacier surface 

must have occurred about 1899, 

that is, at the time of the earthquake. Tarr and Martin did not 

report an actual advance of the 

terminus of Galiano Glacier. The 

changes they noted may have 

been caused by the slumping of 

the unconsolidated deposits on 

which the glacier terminates. 

Hidden Glacier advanced 3 km 

about 1906-07 and this advance 

was by far the greatest described 

by Tarr and Martin. However, 

this glacier flows from an open 

snowfield where possible sources 

of significant avalanching are 

conspicuously absent. 

It is pertinent to note that the 

three steep hanging glaciers on the 

mountain west of Disenchantment 

Bay were not shaken down by 

the 1899 earthquake although this 

area was severely shaken and the 

coastline raised 13 m. However, 

one of these glaciers was so unstable that 6 years later it avalanched into the bay when no 

earthquake occurred (Tarr and 

Martin, 1912, p. 49). This occurrence provides additional evidence that even very steeply 

pitched glaciers are not greatly 

affected by violent earthquakes. 

On the basis of the maps then 

available, Tarr and Mnrtin reported a rough correlation between glacier length and the time 

of terminal activity following the 

earthquake. Table 'I lists the 

lengths of the glaciers, as measured on accurate modern maps, 

and the period of terminal activity for the glaciers they observed. 

Inconsistencies are so large that 

the relationship seems unlikely. 

GLACIER SURGES 

Since Tarr and Martin's work, 

several sudden anomalous advances of glaciers have been reported. Hance (1937) and Moffit 

(1942) described the advance of 

the Black Rapids Glacier in central Alaska. The Muldrow, 

Susitna, and Yanert Glaciers at 

various times also made similar 

advances (Post, 1960). 

Aerial investigations since 1960 

in Alaska and Yukon Territory, 
EFFECTS ON GLACIERS 

TABLE 7.-Lengths and times of sudden movement of glaciers observed by Tarr and Martin 

after the 1899 earthquake 

[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] 

in addition to the studies mentioned above, have led to the 

identification of a type of glacier 

behavior, called a "surge," which 

can be clearly distinguished from 

normal, climatically induced advances (Post, 1965). A typical 

surge is described below. 

After a relatively long interval 

(15-100 years) of virtual stagnation in the terminal area and 

slow increase in thickness in the 

upper part, the glacier is suddenly transformed. An abrupt 

kinematic wave of ice in the upper glacier begins moving very 

rapidly down valley. This movement results in a rapid transfer 

of ice from the upper regions toward the terminus, and the surface of the glacier is chaotically 

broken. A surface displacement 

of 4 Inn or more may take place 

in a single year at the peak of 

the movement. The ice discharge 

may lower the surface as much 

as 150 m in the upper part of 

the glacier. The transferred ice 

overrides and thrusts ahead the 

formerly stagnant ice in the 

lower valley, and here the thickness of the glacier often increases 

as much as 60 m. The volume 

of ice loss in the upper part and 

gain by the lower part of the 

glacier appears to be the same. 

Only rarely does the glacier advance beyond its terminal position before the surge. Apparently the active period of these 

surges does not exceed 34 years, 

regardless of the size of the glacier. Such surges may occur repeatedly in a single glacier; disRemarks 

Slumping of coast of Yakutat Bay in this area probably resulted 

from 1899 earthquake. Changes in glacier may have resulted from 

slumping of underlying alluvial deposits. No advance reported. Terminal advance, probably much 

less than the 1.5 km, shown by 

photographs; advance not observed. 

Rapid movement of ice in valley 

and into terminal lobe 8 km from 

head of glacier; no terminal 

advance. 

Terminal advance of 1,370 m to sea plus unknown movement into sea. Terminus advanced 3 km. Position 

of medial moraines indicates 

steep tributaries on southwest 

side did not furnish more ice 

than normally. Rapid movement of ice in valley 

and terminal lobe; no terminal 

advance. 

Rapid movement of ice in valley 

and into terminal lobe 18 km 

from head of glacier; no terminal 

advance. 

Small advance of terminus (as 

much as 300 m in 11 months). 

A slight further advance occurred 

in 1911 followed by retreat in 

1912 of 0.4 km. 

Rapid movement of ice and slight 

advance of lobate part at least 

40 km from head of glacier. 

tinctive medial-moraine patterns 

frequently provide evidence of 

three or more former surges. 

Conterminous glaciers and even 

individual branches in a single 

large glacier may not surge at 

the same time. Surging glaciers 

are rare but have been reported 

in many parts of the world (see, 

for example, Sharp, 1954, Hattersley-Smith, 1964 ; Dolgushin 

and others, 1963; Post, 1960, 

1965, 1966). 

The "advances" of Tarr and 

Martin seem to have been surges of 

the same kind described above. 

The changes noted in the lower 

parts of the Lucia Glacier (Tarr 

and Martin, 1914, p. 6&69), Atrevida Glacier (1914, p. 69-79), and 

Variegated Glacier (1914, p. 115- 

126) are all typical of glacier 

surges. Even the "glacier flood" 

that Tarr and Martin described 

can be identified on surging glaciers. It is the kinematic wave 

mentioned above, and can be detected on the surface as a zone of 

intense crevassing which progresses rapidly down glacier. 

Evidence of more than 27 glacier surges since 1936 has been 

recorded (fig. 26). At least three 

glaciers have made two or more 

recorded surges. The Variegated 

Glacier surged in 1905, about 

1946, and again in 1964. The 

Kluane Glacier surged in 1941 

and 1961. Tikke Glacier surged 

around 1946 and again in 1963. 

Practically all of the observed 

surging glaciers show evidence of 

having made three or more 

surges. 

Correlation between glacier 

surges and earthquakes of Richter 

magnitude 7 or greater is lacking 

(fig. 26). No glacier surges have 

been recorded in the immediate 

vicinity of any strong earthquake 

since 1899, despite the fact that 

many glaciers are near several of 

the earthquake epicenters. 

Glacier 

Galiano-- --- - - - - 

Miller- - - - - - - - - - 

Atrevida-- - - - - - - 

Haenke--- - - - - - - 

Hidden-- - - - - - - - 

Variegated- - - - - - 

Lucia- - - - - - - - - - 

Nunatak- - - - - - - 

Marvine- - - - - - - - 

Length 

(b) 

8 

5 

13 

14 

19 

21 

24 

32 

48 

Period of 

--- 

Began 

(1899) 

(1899) 

1905 

1905 

( 1906) 

1905 

( 1908) 

1909 

1905 

movement 

Ended 

(1900) 

1901 

1906 

1906 

(1907) 

1906 

( 1909) 

1910 

1906 
Glacier-covered mountain region 

 ark areas show portions of glaciers 

that have surged since 1936. Queried dates are approximate 

Epicenters and magnitudes 

Number indicates year of occurrence 

100 MILES 

I I I 

50 100 KILOMETERS 

~QUBE 28-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. 

Aerial photographs show few 

snow and ice avalanches on glaciers as a result of the 1964 earthquake. Large and small rockslides avalanched onto glaciers at 

several localities. In August 1965 

no clearly defined large-scale dynamic response to avalanche loading or .other effects of earthquake 

shaking had bean found in any 

glacier. 

Large rockslide avalanches traveled several kilometers on glaciers 

at gradients of less than 5O. Two 

of these avalanches occurred many 

months after the earthquake. 

Compressed air may have proClrandell, D. R., and Fahnestock, R. K., 

1985, Rockfalls and avalanches 

from Little Tahoma Peak on Mount 

Rainier, Washington : U.S. Cteol. 

Survey Bull. 1221-A, p. 81-830. 

Dolgushin, L. D., Yevteyev, S. A., 

Krenke, A. N., Rototayev, K. G., 

and Svatkov, N. M., 1983, The recent advance of the Medvczhii Glacier (Pamire) : Priroda, v. 11, p. 

85-92 ; Canada Defence Research 

Board [Ottawa], T 409 R, translated by E. R. Hope, 1964, 8 p. 

Hance, J. H., 1937, The recent advance 

of Black Rapids Glacier: Jour. 

Geology, v. 45, no. 7, p. 775-183. 

Hattersley-Smith, G., 1964, Rapid advance of glacier in Northern Ellesmere Island: Nature, v. 201, no. 

4915, p. 176. 

Mo5t, F. H., 1942, Geology of the Cerstle River district, Alaska, with a 

report on the Black Rapids Glacier : U.S. Geol. Survey Bull. 926-B, 

p. 107-160. 

Nielsen, L. E., 1965, Earthquake-induced changes in Alaskan glaciers : 

SUMMARY AND CONCLUSIONS 

vided an easily sheared lubricating 

layer. Rockslide avalanches are 

so extensive on the Sioux, Saddlebag, and Sherman Glaciers that 

the glacier regimes have been altered, principally because the debris insulates the ice and reduces 

melting. This effect favors future 

advances of these glaciers. 

No apparent changes in icedammed lakes or glacier drainage 

resulted from the earthquake. 

Tidal glaciers show little immediate effects. Tectonic displacements affecting the altitude of glaciers are minor when compared to 

climatic influences. Changes in 

slopes of glaciers are probably too 

small to have observable effects. 

No evidence supporting the 

Earthquake-Advance Theory has 

been found from investigations 

made since the 1964 Alaska earthquake. The nature of recent 

surges, the lack of correlation in 

time and space between them and 

recent earthquakes, and the probrvbility that significant avalanching did not take place on at least 

one of the glaciers observed by 

Tarr and Martin all render the 

Earthquake-Advance Theory suspect. 

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1960, The response of glaciers 

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D42 ALASKA EAR~QUA~E, MARCH 2 7, 19 64 

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T. F., 1964, Geomorphic effects of 

the Good Friday, March 27, 1964, 

earthquake in the Martin River 

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