Re ional Effects 

Copper River 

Basin Area 

G EOLOGICAL SURVEY PROFESSIONAL PAPER 543-E 

THE ALASKA EARTHQUAKE, MARCH 27, 1964: 

REGIONAL EFFECTS 

Effects of the Earthquake 

Of March 27, 1964 

In the Copper River Basin 

Area, Alaska 

By OSCAR J. FERRIANS, JR. 

A description and analysis of the earthquakeinduced ground breakage, landsliding, regional 

uplift and subsidence, and damage to manmade 

structures in the Copper River Basin 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 543-E 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

William T. Pecora, Director 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1966 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 
THE 

ALASKA EARTHQUAKE 

SERIES 

The U.S. Geological Survey is publishing theresults of its investigations of th.e Alaska earthquake 

of March 27, 1964, in a series of six professional 

papers. Professional Paper 543 describes the regional effects of the earthquake. In chapters of this 

volume already published, studies of slide-induced 

waves and seiching at Kenai Lake, geomorphic effects in the Martin-Bering Rivers area, gravity surveys of the Prince William Sound region, and effects 

of the earthquake on Kodiak and nearby islands have 

been reported. 

Other professional papers in the series describe 

field investigations and reconstrqction and the effects 

of the earthquake on communities, on the hydrologic 

regimen, and on transportation, utilities, and 

communications. 

Page 

Abstract _____ ------__________ E1 

Introduction and acknowledgments______________________ 2 

Geographic setting_ _ _ _ _ _ _ _ _ _ _ _ 2 

Physiography_____________ 2 

Climate__________________ 3 

Roads and settlements_____ 3 

Geologic setting__________ _ _ _ _ _ 3 

Bedrock__________________ 3 

Major tectonic elements____ 3 

Unconsolidated deposits____ 6 

Permafrost and seasonal 

frost___________________ 6 

The earthquake and its aftershocks_____________________ 6 

Seismic data______________ 6 

Ground motion ____ ------- 7 

Sound___________________ 7 

1. Index map showing the location of the Copper River 

Basin area _____________ _ 

2. Generalized geologic map of 

the Copper River Basin area ___________________ _ 

3. Map showing major tectonic 

elements of flouth-central Alaska ________________ _ 

4. Map showing recent regional 

uplift and subsidence in 

south-central Alaska ____ _ 

5. Aerial view of the northern 

end of Tonsina Lake ___ _ 

6. Aerial view showing intensely 

fractured· ice along the 

eastern shore of Tazlina 

Lake __________________ _ 

7. Map showing the distribution 

of ground cracks ________ _ 

8. Sketch map of the Little 

Tonsina River landslide site __ 

9. View of pressure ridges on 

Page 

E2 

4 

5 

9 

10 

11 

12 

14 

CONTENTS 

Page 

Geologic effects of the earthquake______________________ E8 

Regional uplift and subsidence_________________ 8 

Changes in ground- and 

surface-water conditions__ 8 

Ground water_________ 8 

Surface water_________ 8 

Cracking of lake and river ice__ 10 

Ground cracks and associa ted landsliding_ _ _ _ _ _ _ _ _ 11 

Terminology__________ 11 

General distribution___ 11 

Geologic controls______ 11 

Little Tonsina River site__ 13 

Other landslide sites____ 13 

N elchina River outwash 

apron______________ 17 

ILLUSTRATIONS 

FIGURES 

Page 

floor of Little Tonsina 

River valley____________ E14 

10. Large ground crack paralleling north side of small hill 

near mile 65, Richardson 

Highway_______________ 15 

11. Photograph of pressure ridge 

on flat surface bordering 

Little Tons ina River_____ 15 

12. Large ground crack formed 

in clearing along south 

shore of lake____________ 16 

13. Aerial view of the large 

braided flood plain of the 

Nelchina River__________ 17 

14. Photograph ortypical ground 

crack in outwash apron of 

Nelchina River__________ 18 

15. Vertical aerial view of Nelchina River delta________ 19 

16. Vertical aerial view of ground 

cracks along and paralleling hingeline on Nelchina 

River delta_____________ 20 

Geologic effects-Continued 

Ground cracks and associated 

landsliding-Continued 

N elchina River delta __ _ Origin ______________ _ 

Lateral extension __ 

Horizontal com- paction _______ _ 

Differential vertical compaction __ 

Snowslides, rockslides, and 

avalanches ___ ----------

Effects of the earthquake on manmade structures ________ _ 

Damage to buildings and 

associated structures ____ _ 

Damage to highways and 

bridges __________ ------- References _______________ - _- __ 

17. Aerial view of north end of 

the large Nelchina River 

delta along the western 

Page 

E17 

23 

23 

23 

24 

24 

25 

25 

25 

27 

Page 

shore of Tazlina Lake____ E21 

18. Aerial view of Kiana Creek 

delta along eastern shore of 

Tazlina Lake____________ 21 

19. Aerial view showing large inundated area along eastern 

shore of Tazlina Lake____ 22 

20. Diagrammatic sections showing mechanism of formation of basic types of 

ground cracks___________ 23 

21. View of pavement surface of 

the Richardson Highway_- 26 

22. Little Tonsina River bridge 

shoved from right to left 

by landslide movement___ 26 

23. Small crack across abandoned section of road on a 

low gravel terrace________ 27 

v 

THE ALASKA EARTHQUAKE, MARCH 27, 1964: REGIONAL EFFECTS 

EFFECTS OF THE EARTHQUAKE OF MARCH 27, 1964, IN THE 

COPPER RIVER BASIN AREA, ALASKA 

The Copper River Basin area is in 

south-central Alaska and covers 17,800 

square miles. It includes most of the 

Copper River Basin and parts of the 

surrounding Alaska Range and the Talkeetna, Chugach, and Wrangell Mountains. 

On March 27, 1964, shortly after 5 : 36 

p.m. Alaska standard time, a great 

earthquake having a Richter magnitude 

of about 8.5 struck south-central Alaska. 

Computations by the U.S. Coast and 

Geodetic Survey place the epicenter of 

the main shock at lat 61.1 o N. and long 

147.7° W., and the hypocenter, or actual 

point of origin, from 20 to 50 kilometers 

below the surface. The epicenter is 

near the western shore of Unakwik Inlet in northern Prince William Sound ; 

it is 30 miles from the closest point 

within the area of study and 180 miles 

from the farthest point. 

Releveling data obtained in 1964 after 

the earthquake indicates that broad 

areas of south-central Alaska were 

warped by uplift and subsidence. The 

configuration of these areas generally 

parallels the trend of the major tectonic 

elements of the region. Presumably a 

large part of this change took place during and immediately after the 1964 

earthquake. 

The water level in several wells in the 

area lowered appreciably, and the water in many became turbid; generally, 

however, within a few days after the 

earthquake the water level returned to 

normal and the suspended sediment settled out. Newspaper reports that the 

By Oscar J. Ferrians, Jr. 

ABSTRACT 

Copper River was completely dammed 

and Tazlina Lake drained proved erroneous. 

The ice on most lakes was cracked, 

especially around the margins of the 

lakes where :floating ice broke free from 

the ice frozen to the shore. Ice on Tazlina, Klutina, an~ Tonsina Lakes was 

intensely fractured by waves generated 

by sublacustrine landslides off the 

fronts of deltas. These waves stranded 

large blocks of ice above water level 

along the shores. River ice was generally cracked in the southern half of 

the area and was locally cracked in the 

northern half. 

In the area of study, the majority of 

the ground cracks occurred within a radius of 100 miles from the epicenter of 

the earthquake. Ground cracks formed 

in flood plains of rivers, in deltas, and 

along the toes of alluvial fans. They 

also occurred locally in low terraces 

adjacent to flood plains, in highway 

and other fill material, along the margins of lakes, along the faces of steep 

slopes of river bluffs and hillsides., and 

in areas cleared of vegetation for several years. 

The ground cracks were restricted to 

areas underlain by unconsolidated deposits where one or more of the following conditions existed : ( 1) permafrost 

was absent or deep lying, ( 2) the 

ground-water table was near the surface, ( 3) bedr6ck was relatively deep 

lying, and ( 4) slopes were steep. Because the earthquake occurred in 

March, seasonal frost was present 

throughout the area. 

Despite the diversity of local conditions, the origin of most of the ground 

cracks can be explained by the following 

mechanisiil.s : ( 1) lateral extension, 

caused by materials moving toward an 

unconfined face such as a lakeshore, 

river bluff, hillside, or terrace escarpment; (2) horizontal compaction, 

caused by repeated alternate compression and dilation (in the horizontal 

direction) of materials in flat-lying 

areas where there are no unconfined 

faces ; ( 3) differential vertical eompaction, caused by the shaking of materials 

that vary laterally in thickness or 

character; and ( 4) combinations of the 

above. 

Snowslides, avalanches, and rockslides were restricted to the mountainous areas surrounding the Copper 

River Basin. They were especially 

numerous in the Chugach Mountains 

which are closest to the epicenter of the 

earthquake. The large amount of snow 

and rock debris that has cascaded onto 

the icefield and glaciers of these mountains, and, probably even more important, the overall disturbance to the ice 

field will affect the regimen of the 

glaciers. 

Most of the damage to manmade 

structures occurred in the southern 

half of the area, and, primarily because 

of the sparsity of population and manmade structures, property damage was 

not great and no lives were lost. 

E1 
E2 ALASKA EARTHQUAKE, MARCH 27, 1964 

INTRODUCTION AND ACKNOWLEDGMENTS 

The Copper River Basin area, as 

defined in this report, covers about 

17,800 square miles in south-central 

Alaska (fig. 1) ; it includes most of 

the Copper River Basin and parts 

of the surrounding mountains. 

0 200 400 MILES I I I I I 

1.-Location of Copper River 

Basin area. 

Its boundary on the east is long 

144°00' W.; on the north, lat 63°-

00' N.; on the west, long 147°40' 

W.; and on the south, approximately coincides with the axis of 

the Chugach Mountains. 

The primary purpose of this investigation was to determine the 

effects of the great Alaska earthquake of 1964 fn the Copper River 

Basin area and the geologic factors 

that tend to control the distribution and character of these effects. 

An understanding of these geologic factors is necessary to evaluPHYSIOGRAPHY 

The Copper River Basin is bordered on the north by the Alaska 

Range, on the west by the Talkeetna ·Mountains, on the south by 

the Chugach Mountains, and on 

ate properly the engineering 

significance of the earthquake. 

Because of the U.S. Geological 

Survey's geologic mapping of the 

Copper River Basin, in progress 

since 1952, the general distribution 

and character of unconsolidated 

deposits in the area are well 

known. Without this work, adequate evaluations of the effects of 

the earthquake would not have 

boon possible during the short time 

available for field investigation. 

Observations of the effects of the 

earthquake in the Copper River 

Basin were made between July 2 

and July 23, 1964. During the 

3:1;4-month interval between the 

occurrence of the earthquake and 

the time when observations were 

made, undoubtedly many earthquake-related features, especially 

subtle ones, were obliterated. Because of this time lag a large part 

of the discussion about earthquake 

da~age to manmade structures is 

based . on eyewitness accounts; 

however, most of the discussion 

concerning the natural earthquake-related features, as distinguished from damage to life and 

property, is based on the author's 

observations and on the study of 

postearthquake aerial photographs. 

GEOGRAPHIC SETriNG 

the east by the Wrangell Mountains. 

The basin floor is a plain of low 

relief into which the major streams 

have cut steep-walled valleys as 

1nuch as 400 feet deep. However, 

Since most ·of the people live 

near the highway, a systematic 

study along the roads provided 

fairly comprehensive coverage of 

damage to manmade structures. 

In the vast, inaccessible areas away 

from the highways, the distribution of earthquake-related features 

was determined by observation 

from light fixed-wing aircraft. At 

several sites where landings were 

possible, these features were examined on the ground. 

I am greatly indebted to all of 

the individuals who provided eyewitness accounts of their experiences during and immediately 

after the earthquake. Rich Houston and Cleo McMahan, both bush 

pilots, not only did an excellent 

job of chauffeuring, but also contributed their own time and energy 

to making critical observations 

pertinent to this study. James 

B. Small of the U.S. Coast and 

Geodetic Survey provided releveling data, Robert M. Chapman of 

the U.S. Geological Survey made 

available an unpublished report 

which included his observations 

along the Richardson Highway 

made soon after the earthquake, 

and several individuals of the 

Alaska Department of Highways 

provided data concerning damage 

to the highways. 

the bordering mountains are extremely rugged and they support 

numerous glaciers, which, along 

with their melt-water streams, 

have cut deep valleys opening into 

the basin. 
EFFECTS IN TRE COPPER RIVER BASIN AREA E3 

The greater part of the area of 

study is drained by the Copper 

River, which originates from large 

glaciers on the northern side of the 

Wrangell Mountains. From its 

source the river flows in a large arc 

around the northern, western, and 

southwestern sides of the Wrangell 

Mountains, and then southward 

through the Chugach Mountains 

into the Gulf of Alaska, Major 

tributaries to the Copper River include the Chistochina, Sanford, 

Gakona, Gulkana, Tazlina, Klutina, Tonsina, and Chitina Rivers. 

The northwestern corner of the 

area is drained by the Susitna 

River which originates from a 

large glacier in the Alaska Range. 

From its source this river drains 

southward to the Copper River 

Basin, then makes a sharp turn 

and flows westward through mountainous terrain to the north end of 

the Susitna Lowland; from here it 

flows southward to Cook Inlet. 

Within the area of study the major tributaries to the Susitna River 

are the Maclaren and Oshetna 

Rivers. 

A small part of the southwestern 

corner of the area is drained by 

the Matanuska River which flows 

westward to Knik Arm of Knik 

Inlet. 

The basin floor is dotted with 

lakes; the three largest are Lake 

BEDROCK 

Mountainous areas around the 

margin of the Copper River Basin 

and prominent hills within the 

basin are underlain by altered 

volcanics and interbedded graywacke and slate, and by virtually 

unaltered sediments, all of which 

have been intruded locally by a 

2314.93 w6.62 

Louise, Crosswind Lake, and Ewan 

Lake. Tazlina, Klutina, Tonsina, 

and Paxson Lakes are large water 

bodies occupying deep valleys in 

the mountainous areas surrounding the basin. 

CLIMATE 

The Copper River Basin area 

has an arctic continental weather 

regime with short warm summers 

and long cold minters. Mean annual temperature, as recorded at 

the Gulkana Federal Aviation 

Agency Station in the east-central 

part of the area of study, is 27"F., 

and mean annual precipitation is 

12 inches. These climatic conditions are signific:tnt to this study 

because they are conducive to the 

formation and preservation of 

permafrost (perennially frozen 

ground) -and the presence or 

absence of permafrost is significant 

in relation to the distribution and 

cha~acter of earthquake effects. 

ROADS AND SETTLEMENTS 

Large segments of two major 

*4laska highways cross the Copper 

River h as in area. Both highways 

are paved two-lane roads which 

connect coastal cities in southcentral Alaska with interior 

Alaska. The Glenn Highway, 314 

GEOLOGIC SEWING 

wide variety of igneous rocks. 

Extensive areas are underlain also 

by a considerable thickness of unaltered basaltic and andesitic 

lava. These rocks range in age 

from middle Paleozoic to Pleistocene. The distribution of bedrock within the area of study is 

shown on figure 2 (next page). 

miles long, extends from Anchorage to Tok Junction on the Alaska 

Highway ; t,he Richardson Highway, 365 miles long, extends from 

the ice-free port of Valdez to Fairbanks. Locations along these 

highways are designated by the 

number of miles from the point of 

origin of the highway-along the 

Glenn Highway, miles from Anchorage, and along the Richards011 

Highway, miles from Valdez. 

Other roads within the area of 

study include the Edgerton Highway and the Lake Louise Road. 

The Edgerton Highway, a twolane gravel road in the southeastern corner of the area, is 39 miles 

long and corlnecb Chitina with the 

Richardson Highway. The Lake 

Louise Road, also a two-lane 

gravel road, leads north from mile 

160, Glenn Highway, for approximately 19 miles to Lake Louise. 

The settlements within the area 

are concentrated along or near the 

major highways. Glennallen, the 

principal settlement, of the area, 

with a population of around 200 

people, is near the junction of the 

Glenn and Richardson Highways. 

Other settlements include Chitina, 

Copper Center, 3ulkana, Gakona, 

Chistochina, and Paxson. Several 

roadhouses and some service enterprises are located along the highway between these settlements. 

MAJOR TECTONIC 

ELEMENTS 

There are six major tectonic elements within the area of study 

(fig. 3, p. 6). From north to 

south, they consist of the Alaska 

Range geosyncline, the Talkeenta 

geanticline, the Matanuska geosyncline, the Seldovia geanticline, 
E4 

Base from Anchorage, World (N . Am erica) 

1:1000000 sca le, compiled by 

Army Map Service 

Coarse-grained unconsolidated deposits 

of Recent age 

ALASKA EARTHQUAKE, MARCH 27 , 1964 

0 

EXPLANATION 

Fine- and coarse-grained 

~ 

~ unconsolidated 

deposits of Pleistocene age 

Bedrock ranging 

-

in age from middle 

Paleozoic to Pleistocene 

10 20 30 40 MI LES 

2.-Generalized geologic map of the Copper River Basin area. Geology compiled by Ferrians, Nichols, Williams, and Yehle; 

Grantz (pl. 23 in Andreason and others, 1964); and Coulter and Coulter (1962) . 
EFFECTS IN THE COPPER RIVER BASIN AREA 

150" 148° 146. 144° 

0 50 

i 4~~" 

Base from U.S. Geologica l Survey 1:2 500 000 

JOO MILES / 

3.-Major tectonic elements of south-central Alask!a (after Payne and Dutro, in Miller and others, 1958, pl. 2). Geosynclinal 

area (troughs) shown by light stippling; geanticlinal areas (arches), by heavy stippling; and the Copper River Basin, by 

diagonal lines. 

E5 
E6 

and the Chugach Mountains geosyncline (Payne and Dutro, in 

Miller, and others, 1959, pl. 2). 

In the central part of the area the 

Cenozoic Copper River Basin is 

superimposed on several of the 

other tectonic elements. 

UNCONSOLIDATED 

DEPOSITS 

In the mountainous areas surrounding the Copper River Basin 

the floors of the major valleys are 

underlain predominantly by unconsolidated sediments of Pleistocene and Recent age. These sediments are chiefly outwash gravel 

deposited by glacier-fed streams 

and till deposited by glaciers 

which formerly covered the valley 

floors. Locally, significant thicknesses of colluvial deposits are 

present. 

The greater part of the basin itself is underlain by lacustrine, glacial, and fluvial sediments of 

Pleistocene and Recent age (Karlstrom and others, 1964). In the 

ALASKA EARTHQUAKE, MARCH 27, 1964 

east-central part of the basin, these 

deposits are quite thick. The exact thickness ~s unknown; however, as much as 400 feet is well 

exposed in bluffs along the deeply 

entrenched rivers, and near Glennallen a water well 502 feet deep 

bottomed in unconsolidated deposits. In the western part and 

along the margin of the basin, 

these deposits generally overlie 

bedrock at relatively shallow 

depths. The distribution of unconsolidated deposits within the 

area of study is shown on figure 2. 

PERMAFROST AND 

SEASONAL FROST 

Permafrost and seasonal frost 

were important factors in determining the distribution and character of ground cracks and landslides. Most fine-grained unconsolidated deposits in the Copper 

River Basin are perennially frozen 

from 1 to 5 feet below the surface 

to depths of as much as 200 feet. 

In similar areas that have been 

cleared of vegetation for .several 

years, such as those along the highway net or in settled areas, the 

permafrost table (top of permafrost) occurs from 10 to 20 feet below the surface. In contrast to 

the fine-grained deposits, the 

coarse-grained gravel deposits 

along the major streams generally 

are free of permafrost. Permafrost generally is also absent near 

large deep lakes because of the 

enormous amount of heat held in 

these large bodies of water. In the 

Chugach Mountains south of the 

basin, permafrost occurs as isolated masses where local conditions are favorable for its formation and preservation (Ferrians, 

1965). 

Seasonal frost generally penetrates to depths from 2 to 4 feet in 

poorly drained environments such 

as marshes; however, in welldrained environments such as 

gravel terraces, seasonal frost generally penetrates from 10 to 20 

feet. 

THE EARTHQUAKE AND ITS AFTERSHOCKS 

SEISMIC DATA 

Computations by the U.S. Coast 

and Geodetic Survey ( 1964, p. 30) 

placed the time of origin of the 

earthquake at shortly after 5 : 36 

p.m. Alaska standard time, March 

27, 1964, the epicenter at lat 61.05° 

N. and long 147.50° W., and the 

hypocenter, or actual point of 

origin, at about 20 kilometers 

(about 12% miles) below the surface. Later computations, based 

on more data, place the epicenter 

at lat 61.5° N. and long 147.7° W. 

and the hypocenter at a depth 

between 20 and 50 kilometers. 

Estimates of the Richter magnitude of the earthquake, from four 

United States stations, range from 

8.4 to 8% and place it among the 

historically great earthquakes. 

The epicenter, which is near the 

west shore of Unakwit Inlet in 

northern Prince William Sound, 

is 30 miles from the closest point 

within the area of study and 180 

miles from the farthest point. 

During the first month after the 

main shock more than 7,500 aftershocks were recor<ied at the five 

seismograph stations that were installed in the epicentral area soon 

after ·the main shock occurred 

(Algermissen, 1965, p. 2). Press 

and Jackson (1965, p. 867) reported that approximately 12,000 

aftershocks, having a magnitude 

equal to or greater than 3.5, occurred during a 69-day period 

after the main shock. 

Press and Jackson ( 1965, p. 868) 
EFFECTS ~ THE COPPER RIVER BAS~ AREA E7 

estimated that a line distribution 

of 100 underground nuclear explosions, totalling 100 megatons each, 

would be necessary to equal the 

seismic energy released by the 

Alaska earthquake. 

GROUND MOTION 

The tremendous amount of 

energy released during the ea.rthquake caused severe ground shaking throughout most of the southern half of the area of study. 

However, locally there was variation in the reported intensity and 

duration of shaking. Most observers reported that the ground motion lasted 3-5 minutes. Gutenberg (1956, 1957) demonstrated 

that within a small area the duration and intensity of ground shaking can vary considerably depending upon the character of the underlying materials. For example, 

water - saturated unconsolidated 

deposits will be affected more than 

similar unconsolidated deposits 

which are dry, and much more 

than hard crystalline bedrock. 

From Glennallen southward 

and westward the ground motion 

generally was described -as having 

either a jarrmg effect or a strong 

rolling effect on most dwellings, 

whereas north of Glennallen most 

people reported a gentle rolling 

effect, like swells on the ocean. 

People reported seeing trees and 

telephone and power poles being 

whipped hack and forth by the 

ground motion. 

Many people reported seeing the 

ground undulate in waves like 

those generated on large bodies of 

water. Unfortunately, during a 

great earthquake it is difficult for 

individuals to make objective observations. However, one observer estimated that at the junction of the Glenn and Richardson 

Highways, 100 miles from the 

main epicenter, these waves were 

about 10 feet apart and about 3 

feet high. Other reliable witnesses estimated that the ground 

waves near Slana, 165 miles from 

the main epice.nter, were 50-60 feet 

apart and 18-20 inches high. All 

the witnesses stated that the waves 

moved from the southwest to the 

northeast. 

Even though many individuals 

have reported visible ground 

waves during major earthquakes, 

especially in flat-lying areas underlain by water-saturated unconsolidated deposits, many seismologists discount such occurrences. 

One of the main reasons for this 

skepticism is that ground waves 

recorded on seismographs have 

crests and troughs too small to be 

seen, commonly no more than 0.004 

inch for large surface .waves and 

hardly ever more than 0.020 inch 

(Leet and Leet, 1964, p. 79) ; furthermore, praotically all of these 

waves travel too fast to be seen. 

Other explanations used to discount the existence of visible 

ground waves include optical, 

physiological, and psychological 

illusions. 

The opinion of Eiby (1957, p. 

26) is typical of that of many seismologists. He presents arguments against the existence of visible ground waves and then states, 

"However, something of the kind 

has so often been reported in good 

faith that it must be supposed 

that the violent shaking so effects 

a man as to produce an illusion of 

this kind. With this demonstration of human fallibility it· is as 

well to pass to the problem of instrumental recording." 

In spite of the difficulty of explaining the origin of such phenomena, many workers have concluded that visible ground waves 

do exist. These include Dutton 

(1890, p. 267-268), Oldham (1899, 

p. 4-41), the State Earthquake Investigation Commission (1908, v. 

1, p. 380-381), Knott (1908, p.18), 

Fuller (1912, p. 57), Imamura 

(1937, p. 75), and India Geological Survey Officers and Roy (1939, 

p. 29-30). 

In a more recent publication, 

Richter ( 1958, p. 132) concludes 

that there is almost certainly a real 

phenomenon of visible progressing 

or standing waves on soft ground, 

but he thinks the effect may be associated with earth lurching, with 

which it may be confused. The 

phenomenon of visible ground 

waves obviously poses a perplexing problem that needs further 

study, but the evidence in the Copper River basin area tends to fortify the conclusion that visible 

ground waves do exist. 

SOUND 

A few people heard sounds 

which presumably were associated 

with the earthquake. Generally 

the sound was described as a rumbling or roaring like distant thunder. This type of phenomenon 

has occurred during many other 

g r e a t earthquakes. Thompson 

(1929) and Kingdon-Ward (1951, 

p. 130, and 1953, p. 172) have described unusually loud sounds 

heard during two such earthquakes. 

Even though there is some disagreement on certain points, the 

perception of sound is fairly well 

explained by seismologists : the 

sound waves are produced directly 

by the transfer of elastic wave 

energy from the ground to the air 

(Richter, 1958, p. 128). 

Some earthquakes have transferred enough energy to the air 

that sensitive barographs several 

hundred miles from the epicenter 

were affected. Gutenberg and 

Benioff ( 1939) first described this 

effect. 
E8 ALASKA EARTHQUAKE, MARCH 27, 1964 

GEOLOGIC EFFECTS OF THE EARTHQUAKE 

REGIONAL UPLIFT AND 

SUBSIDENCE 

During the summer of 1964 the 

U.S. Coast and Geodetic Survey 

completed aproximately 900 miles 

of first-order leveling in Alaska 

areas affected by the earthquake. 

About 680 miles of this was releveling of previously established 

first-order leveling. Releveling 

was accomplished between Seward 

and Anchorage via The Alaska 

Railroad, between Anchorage and 

Glennallen via the Glenn Hi <Y h- b 

way, and between Valdez and a 

point 15 miles southeast of Fairbanks via the Richardson Highway. 

A large part of the resurveyed 

net was first leveled in 1922 and 

1923; new stations were established and others releveled along 

parts of this net in 1943, 1944, and 

1952. Examination of these data 

suggests that there have been 

minor changes in altitude prior to 

1964; however, a large part of the 

change determined by the 1964 

releveling must have occurred during and immediately after the 

earthquake. Changes in altitude 

of some stations, all on unconsolidated deposits, were obviously 

anmnalous and undoubtedly represented changes caused by local 

pheno~ena such as frost heaving, 

slumping, or thawing of permafrost. These changes in altitude 

we~e not considered in evaluating 

regional uplift and subsidence. 

Recent regional changes in altitude in south-central Alaska are 

sho~n in figure 4, compiled primarily from releveling data supplemented with data from Grantz 

Plafker, and Kachadoorian (1964: 

p. 4). Because of the lack of control points, the location of the isobase lines are only approximate. 

In spite of the sparsity of control 

points, it is obvious that a broad 

area, including a large segment of 

the Chugach Mountains, part of 

the Talkeetna Mountains, most of 

the Copper River Basin, and the 

Cook Inlet Lowland, did subside, 

and that large areas to the south 

and north of the subsided area 

were uplifted. The subsided area 

fo~ms an arcuate trough sloping 

gently to the west and to the southwest. The maximum determined 

amom1t of subsidence was about 6 

feet near Portage. The available 

data indicate that the-uplifted area 

north of the trough forms a gentle 

arch having a maximum determined uplift of almost 1 foot. 

Uplift to the south of the trough 

was 1nuch greater and was reported to be at least 33 feet on land 

(Plafker, 1965, p. 1679). 

The fact that the configuration 

of the subsided and uplifted areas 

generally parallels the trend of the 

major elements of the region (see 

fig. 3) suggests a genetic relationship. The southern two-thirds of 

the area of study is within the eastern part of the trough, and the 

northern one-third of the area covers a part of the southern edge of 

the uplifted arch north of the 

trough (fig. 4). 

CHANGES IN GROUND- AND 

SURFACE-WATER CONDITIONS 

GROUND WATER 

The water level in several wells 

in the area' lowered appreciably, 

and the water :from many wells 

became turbid. Generally within 

a few days after the earthquake, 

the water level returned to normal 

and the suspended sediment settled out. Three wells in the Glennallen area were reported to have 

gone dry after the earthquake. 

Water from a spring on the 

north side of the Glenn Highway 

near mile 140 was reported to have 

been turbid and salty to the taste 

after the earthquake, but within a 

few days the condition of the water returned to normal. 

Ground water near the surface 

caused an increase in the intensity 

and duration of ground inotion 

which, in turn, caused ground 

breakage. In many areas ths 

ground water, along with finegrained sediments, was ejected to 

the surface through cracks and was 

sprayed into the air. These phenomena are called "earthquake 

~ountains" and have been reported 

In many areas during major earthquakes, for example: the Charleston earthquake of 1886 (Dutton, 

1904, p. 296-298) ; the California 

earthquake of 1906 (State Earthquake Investigation Commission, 

1908, p. 402-404); the Pleasant 

Valley, Nev., earthquake of 1915 

(Jones, 1915, p. 196); the Japanese earthquake of 1923 (Imamura, 1937, p. 74); the BiharNepal earthquake of 1934 (India 

Geological Survey officers and 

Roy,1939,p.33-34,185-187);and 

the Alaska earthquake of 1958 

(Davis and Sanders, 1960, p. 248-

250). 

SURFACE WATER 

Soon after the earthquake, newspapers reported that the Copper 

River was dry in its lower reaches 

and that Tazlina Lake had 
EFFECTS IN THE COPPER RIVER BASIN AREA E9 

4t 146' 

Base from U.S. Geologica l Su rvey 1:2 500 000 

4.-Areas of recent regional uplift (hachured) and subsidence (stippled). Isobase lines are solid where control is good and 

dashed where control is poor. Northernmost 0-isobase line ~epresents approximate limit of detectable change in altitude. 
El0 ALASKA E;ARTHQUAI(E, MARCH 27, 1964 

&-View, to the northeast, of the northern end of Tonsina Lalre showing intensely 

fractured ice and 1arge.blocks of ice stranded above water level along the shore. The 

lake is about half a mile wide at this point. Photograph by U.S. Army, April 8,1964. 

drained. Examinations by personnel of the U.S. Geological Survey and the A.laska Department of 

Highways, several days after the 

earthquake, produced no evidence 

that the Copper River was, or had 

been, completely dammed. Water 

was flowing in the main channels 

of the Copper River and the water 

in Tazlina Lake was near its normal level for that time of the year. 

Large waves were generated on 

Tazlina, Klutina, and Tonsina 

Lakes by sublacustrine landslides 

off the fronts of deltas. These 

waves stranded large blocks of ice 

above water level along the shores 

(fig. 5), and at the outlet of Tazlina Lake, sediment and large 

blocks of ice were carried over the 

rapids and a short distance down 

the Tazlina River. 

A large snowslide near mile 50, 

Richardson Highway, dammed 

the Tiekel River, and ice jams near 

miles 74 and 78.5, Richardson 

Highway, dammed the Tonsina 

~iver: In both places, explosives 

were used to blast channels 

through the obstructions to prevent the river from flooding the 

highway. 

CRACKING OF LAKE AND 

RIVER ICE 

The earthquake caused the ice 

on most lakes to crack, especially 

around the margins of the lakes 

where the floating ice broke free 

from the ice frozen to the shore. 

In addition to the breakage along 

the shores of the lakes, a few linear 

cracks commonly formed at a tmgent to the shorelines. In many 

places these linear cracks extended 

completely across the lakes. 

Tazlina, Klutina, and Tonsina 

Lakes were major exceptions to 

this general pattern. Ice on Klutina Lake and Tonsina Lake was 

highly fractured throughout (fig. 

5). On Tazlina Lake the ice on 

the northern half of the lake was 

highly fractured (fig. 6), but ice 

on the southern half was fradured 

only around the margin, and a few 

linear cracks were formed across 

the lake. The geabr intensity of 

the cracking of ice on these lakes 

was caused by water waves generated by sublacustrine landsliding 

off the fronts of large deltas built 

out into the lakes. 

River ice c r a c k e d locally 

throughout the area of investigation. At several places along the 

Nelchina, Sanford, and Copper 

Rivers the cracks formed a systematic reticulate pattern, easily 

recognized on aerial photographs. 
EFFECTS IN THE COPPER RIVER BASIN AREA 

6.-View, to the east, showing intensely fractured ice along the eastern shore of 

Tazlina Lake, across from the large Nelchina River delta. Large blocks of ice 

stranded above water level along the shore are easily discernible, but the intense 

fracturing of ice away from the shore is obscured by the refreezing of the lake 

water and by a postearthquake snowfall. The segment of shoreline shown in this 

photograph is about half a mile long. Photomaph by U.S. Army, April 8, 1964. 

GROUND CRACKS AND ASSOCIATED LANDSLIDING 

I TERMINOLOGY 

The terminology for ground 

cracks caused by earthquakes has 

I been inconsistently used in the 

I literature. The terms "fissure," \ "fracture," "furrow," and "ground 

crack" have been used more or less 

synonymously. However, on the 

basis of priority the terms "fisI sure" and "fracture" should be reI served for two types of ground 

cracks of different origin. Oldham (1899, p. 86) proposed the use I 

? of the term "fissure" for ground 

cracks formed by forces acting at 

the surface, and the term "fracture" for ground cracks formed by 

forces acting at depth, such as 

movement along a buried fault. 

In many places it would obviously 

be difficult to distinguish between 

the two types of ground cracks. 

221-693 0-66--3 

For this reason and becauw of 

other inherent difficulties with this 

classification, I have used the general term "ground crack" which 

has no specific generic connotation. 

GENERAL DISTRIBUTION 

In the area of study, the majority of the ground cracks occurred within a radius of 100 miles 

from the epicenter of the earthquake. Ground cracks formed in 

the flood plains of rivers, in deltas, 

and along the toes of alluvial fans. 

They also occurred locally in low 

terraces adjacent to flood plains, in 

highway and other fill material, 

along the margins of lakes, along 

the face of steep slopes of river 

bluffs and hillsides, and in areas 

cleared of vegetation. 

The overall distribution pattern 

of ground cracks within the area 

of study indicates that the cracks 

were not localized in regional 

linear zones (fig. 7), and thus suggests that they were not caused by 

fault movement in bedrock beneath 

the unconsolidated d e p o s i t s . Rather, the distribution pattern 

indicates that local geologic factors 

controlled the distribution of the 

cracks. Nevertheless, the possibility that fault movement at 

depth did cause ground cracks to 

form locally can not be definitely 

eliminated. 

GEOLOGIC CONTROLS 

The ground cracks were restricted to areas underlain by unconsolidated deposits (see fig. 2) 

where one or more of the following conditions existed : (1) permafrost was absent or deep lying, (2) 

the ground-water table was near 

the surface, (3) bedrock was relatively deep lying, and (4) slopes 

were steep. Because the earthquake occurred in March, there 
El2 

Base from Anchorage, World (N Amenca) 

1 1 000 000 scale, complied by 

Army Map Service 

ALASKA EARTHQUAKE, MARCH 27, 1964 

EXPLANATION 

• 

Area where ground cracks were 

observed, July 1964 

0 10 20 30 40 I'-1 1LES 

7.-Distribution of ground cracks in the Copper River Basin area. 
EFFECTS IN THE COPPER RIVER BASIN AREA El3 

was a variable thickness of seasonal frost throughout the area. 

Most ground cracks occurred in 

coarse-grained unconsolidated deposits, but some occurred in finegrained deposits, generally in 

proximity to steep slopes, along the 

shores of lakes, or in areas cleared 

of vegetation for several years. 

Where well-drained unconsolidated deposits were thin, overlying bedrock at shallow depths, 

grounds cracks generally did not 

form. 

Permafrost which extends from 

near the surf ace to depths as great 

as 200 feet is widespread in the 

Copper River Basin area, but generally was absent in areas underlain by coarse-grained deposits in 

which ground cracks formed (see 

figs. 2, 7). Permafrost generally 

was absent also near large deep 

lakes, and consequently, ground 

cracks occurred locally along the 

shores. In areas where ground 

cracks fonned in fine-grained deposits, the impervious permafrost 

table generally was from 10 to 20 

feet below the surface; in flat-lying areas this situation permitted a 

water-saturated zone to exist between the pemnafrost table and the 

base of the seasonal frost at the 

surface. 

The effect of permafrost on the 

distribution of ground cracks becomes apparent if one considers 

that a thick layer of ice-rich permafrost behaves more like bedrock 

than like unconsolidated deposits 

and that, according to Gutenberg 

(1956, 195'7)) the intensity and 

duration of ground motion at the 

same distance from the epicenter 

may be 10 times as great in wate,rsaturated unconsolidated deposits 

as in crystalline bedrock. Naturally, other conditions being 

equal, ground breakage will be 

most severe in areas receiving the 

greatash intensity of ground motion for the longest period of time. 

When the earthquake occurred 

in the latter part of March, seasonal frost, which was near its 

annual maximum penetration, 

formed a thin, brittle layer extending from the surf ace of the ground 

to variable depths, depending 

upon local conditions. The 

ground motion, where it was intense, broke this brittle layer, and 

thereby formed the ground cracks. 

At many places along slopes (unconfined faces), the seasonal frost 

probably prevented ground breakage, whereas in flat-lying areas underlain by permafrost-free watersaturated materials, the seasonal 

frost facilitated ground breakage. 

In most areas where severe 

ground breakage occurred, the 

ground-water table was no more 

than 15 feet from the surface, and 

generally just a few feet. In some 

places, large concentrations of vadose water were perched on top of 

the impervious permafrost. In 

areas where the ground-water table was within a few feet of the 

surface, permafrost generally was 

absent; in areas where vadose water was perched on top of permafrost, the permafrost table was 4- 

atively deep lying. Under both 

conditions the unconsolidated deposits beneath the seasonal frost 

were saturated with water, and 

consequently, were subjected to 

greater intensity and duration of 

ground motion than unconsolidated deposits perennially frozen 

or those not saturated with water. 

In many parts of the area, 

ground cracks formed on or near 

a steep slope, which provided an 

unconfined face for the lateral extension of materials. These 

ground cracks generally paralleled 

the slope and occurred either on 

the face of the slope or behind it. 

Landforms with relatively steep 

slopes, along which ground cracks 

occurred, include hillsides, lakeshores, river bluffs, and terrace 

escarpments. 

LITTLE TONSINA RIVER SITE 

The Little Tonsina River landslide site (fig. 8, next page) is in 

the southern part of the area, on 

the southwestern side of the 

Richardson Highway at mile 65. 

Landsliding occurred along the 

northwestern side of a small hill 

underlain by unconsolidated silt, 

sand, and gravel deposits. Lateral 

movement of segments of the hill 

toward the northwest caused several large ground cracks to form 

on and parallel to the face of the 

hill and pressure ridges to develop 

on the floor of the Little Tonsina 

River valley (fig. 9). One of the 

large ground cracks formed by the 

lateral extension of materials toward an u,nconfined face (hillside) 

is shown in figure 10, and a pressure ridge developed in front of 

the slide area is shown in figure 11. 

The horizontal forces that formed 

the ridge were transmitted 

through a layer of seasonally 

frozen peat and silty sand, approximately 2 feet thick, overlying 

water-saturated silty sand. Locally, water-saturated silty sand 

was ejected to the surface through 

cracks in the seasonally frozen 

layer. 

OTHER LANDSLIDE SITES 

Other landslides include a large 

one at the mouth of Klutina Lake 

which caused the Klutina River to 

be diverted, several small ones 

along bluffs of the major rivers of 

the area, and numerous small 

slides marginal to lakes (see fig. 

7) . Ground cracks formed along 

margins of lakes by lateral movement of materials. An example is 

shown in figure 12 (p. 16). 
ALASKA EARTHQUARE, MARCH 2 7, 19 64 

8. Sketch rnap of the Little Tonsina River landslide site. 

9.-View, to the northwest, showing pressure ridges on floor of Little Tonsina River 

valley near mile 65, Richardson Highway; pressure ridges (indicated by arrows) 

caused by landsliding on face of hill. 
EFFECTS IN THE COPPER RIVER BASIN AREA 

10.-One of several large ground cracks paralleling northwest side of small hill 

near mile 65, Richardson Highway. Crack, formed in fine- to medium-grained 

sand, has maximum width of 3 feet and depth of abut 5 feet. The laterd extension of materials down the side of the hill caused the ground cwcks and also caused 

pressure ridges to form on level ground several hundred feet in front of the base 

of hill. 

11.-Pressure ridge, 6 feet high, on flat surface bordering Little Tonsina Ever' 

near mile 65, Richardson Highway. Crest of ridge broken irregularly by upward 

flexing of frozen peat caused by landsliding on a nearby hillside. 
ALASKA EARTHQUAKE, MARCH 2 7, 1 9 64 

12.-Large ground crack formed in clearing along south shore of lake about twotenths of a mile north of mile 158, Glenn Highway. Maximum width of crack is 

4 feet and depth is 6 feet. This ground crack is one of several that generally parallel 

the lakeshore. 
EFFECTS IN THE COPPER RIVER BASIN AREA El7 

13.-View, to the east, of the large braided flood plain of the Xelchina River 8 miles north of the terminus of the Nelchina Glacier. 

NELCHINA RIVER OUTWASH during the earthquake. One of area. The delta is approximately 

APRON the most significant characteristics 21h miles wide at its widest point 

The Nelchina River outwash 

apron, in the southwestern part of 

the area, is underlain by silty sand 

and gravel, is approximately 10 

miles in length, and averages about 

2 miles in width (fig. 13). The 

unvegetated parts of this outwash 

apron were literally crisscrossed 

with ground cracks that generally 

ranged from 1 to 2 feet in width 

and extended for great distances 

across the flood plain (fig. 14, next 

page). Measurement of the rather 

systematic reticulate pattern of 

ground breakage at several points 

suggested a preferred orientation 

of N. 35" W. and N. 50" E. Silty 

sand, locally including pebbles, 

and large quantities of water were 

ejected from many of the cracks 

- 

of this site was the absence of any 

unconfined face toward which the 

materials could move, and consequently, form ground cracks. An 

explanation for the origin of 

ground cracks in such flat-lying 

areas is given below on page E23. 

Extensive ground breakage, 

similar to that in the Nelchina 

River outwash apron, also occurred in the flood plains of the 

lower parts of the Chitina and 

Copper Rivers, and, locally, in 

flood plains of other streams (see 

fig. 7). 

NELCHINA RIVm DELTA 

The Nelchina River delta (figs. 

15-17, p. 19-21) is along the 

northwestern side of Tazlina Lake 

in the southwestern part of the 

, e 

and generally is underlain by silty 

sand and gravel. Undoubtedly, 

finer grained deltaic deposits are 

present at depth. All of these deposits are free of permafrost, and 

the ground-water table is within a 

few feet of the surface. Extensive 

ground breakage in the delta included a concentration of cracks 

along, and generally parallel to, a 

hingeline that crossed the delta. 

This hingeline is conspicuous in 

figure 15 because most of the snow 

co-cer on the downslope side has 

been removed by water and sediment ejected from ground cracks. 

Figure 16 shows ground cracks in 

the central part of the hingeline, 

and figure 17 shows cracks at the 

northern end of the delta. 
ALASKA EARTHQUAKE, MARCH 27, 1964 

14.-Typical ground crack in outwash 'apron of Nelchina River 2 miles north of terminus of Nelchina Glacier; crack about 

2 feet wide at widest point. Note how crack was deflected slightly in crossing swale in foreground. Standing water in swale 

marks the shallow ground-water table. Dark line behind man is trace of intersecting crack. 
I EFFECTS IN THE COPPER RIVER BASIN AREA El9 

15.-The Nelchina River delta. Hingeline across the delta is conspicuous because,.most of the snow has been removed from the 

downslope side by water and sediment ejected from ground cracks. The pocrition and character of the water-delta interface or 

shoreline in 1948 compared with the postearthquake shoreline indicate that large segments of the delta front slid into the lake. 

IJhotograph by U.S. Coast and Geodetic Survey, April 10,1964. 
E20 ALASKA EARTHQUAKE, MARCH 2 7, 19 64 

16.-Ground cracks along and paralleling hingeline on Nelchina River delta. Photograph by U.S. Geological Survey, 

October 1964. 
The available evidence suggests 

that the delta surface subsidedthe greatest amount of subsidence 

occurring at the front of the delta 

and progressively lesser amounts 

upslope from the front. This differential subsidence resulted in a 

broad cambering of the delta surface which caused the concentration of tension cracks along the 

hingeline. 

The position and character of 

the water-delta interface in 1948 

as compared with the position and 

scalloped character of the postearthquake interface (see fig. 15) 

indicate that not only was there 

subsidence but that large segments 

of the delta front slid into the lake. 

This sublacustrine landsliding 

generated large waves that severely fractured the ice on the 

northern part of the lake and 

17.-North end of the large Nelchina River delta along the western shore of Tazlina stranded large of ice above 

Lake. Nwte the reticulate pattern of ground cracks which are as much as 6 feet water level along the shore. Large 

wide. quantities of sediment and ice were 

discharged through the outlet of 

the lake into the channel of Taz18.-View showing flooding of Kiana Creek delta along eastern shore of Tazlina 

Lake. 

lina River. Similar sublacustrine 

landsliding occurred off the fronts 

of deltas in Klutina Lake and in 

Tonsina Lake. 

The flooded ddta of Kiana 

Creek along the eastern shore of 

Tazlina Lake is shown in figure 

18. Subsidence, probably caused 

by compaction of unconsolidated 

sediments, and lateral movement 

of materials toward the lakeshore 

caused flooding of the delta and 

the formation of numerous ground 

cracks. A large area along the 

eastern shore of Tazlina Lake just 

south of the Kiana Creek delta was 

inundated (fig. 19). This area, 

which is part of an old alluvialfan delta of Kiana Creek formed 

when the creek was a much larger 

stream, was subjeoted to changes 

similar to those that occurred at 

the Kiana Creek delta. 
E22 ALASKA EARTHQUAKE, MARCH 27, 1964 

19.-Large inundated area along eastern shore of Tazlina Lake just south of the Kiana Creek delta. Lateral movement and 

vertical compaction of materials along lakmhore caused numerous ground cracks to form and the area to subside. Note normal 

beach (indicated by arrow) in the distance. 
EFFECTS IN THE COPPER RIVER BASIN AREA E23 

A 

B 

c 

LATERAL EXTENSION 

Pressure ridges Y' 1 __...../ 

\ ./ -- ~-­ ---

I 

HORIZONTAL COMPACTION 

J 

I 

/ 

---

DIFFERENTIAL VERTICAL COMPACTION 

20.-Diagrammatic sections showing meehanism of formation of basic types of 

ground cracks in unconsolidated deposits in the Copper River Basin area. 

ORIGIN 

As already explained, the 

ground cracks within the area of 

study were formed in unconsolidated deposits under a variety of 

geologic conditions. Despite this 

diversity of local conditions, the 

origin of most of the ground 

cracks can be explained by the following mechanisms: ( 1) lateral 

extension, caused by materials 

moving toward an unconfined face 

such as a lakeshore, river bluff, 

hillside, or terrace escarpment; 

(2) horizontal compaction, caused 

by repeated alternate compression 

and dilation (in the horizontal 

direction) of materials in Hatlying areas where there are nounconfined faces ; ( 3) differential 

vertical compaction, caused by the 

shaking of materials that vary laterally in thickness or character; 

and ( 4) combinations of the above. 

Figure 20 shows the mechanism of 

formation of the three basic types 

of ground cracks. 

LATERAL EXTENSION 

Lateral-extension ground cracks 

occurred on and behind relatively 

steep slopes (fig. 20, section .A.). 

These steep slopes · provided an 

unconfined face toward which materials moved laterally, and in 

some places the movement was 

great enough to be considered 

landsliding. Generally the cracks 

formed parallel to the slope or 

unconfined face. 

HORIZONTAL COMPACTION 

The term "horizontal compaction" is used in this report for the 

earthquake-induced mechanism 

that causes unconsolidated materials to lose volume in the horizon-
E24 

tal direction, and consequently, 

causes ground cracks to form (fig. 

20, section B). In flat-lying areas 

where there are no unconfined 

faces toward which the materials 

can move laterally, the very presence of numerous ground cracks, 

that extend for great distances 

indicates that the materials have 

lost volume in the horizontal 

direction. 

In March when the earthquake 

occurred, seasonal frost had penetrated the surficial materials to a 

depth of several feet and formed a 

hard brittle surface layer. Because of the extremely cold weather in the area, the frozen surficial 

materials were in a state of tension. 

This frozen layer probably was 

initially cracked by ground waves 

flexing the surface. 

The earthquake-induced ground 

waves must have subjected the 

water-saturated sediments beneath 

the seas$mal frost to repeated alter~ 

nate compression and dilation in 

the horizontal direction, the net 

result of these forces being horizontal compaction. Large quantities of water and silt- and sandsized material were ejected from 

the cracks, and sediment particles 

were rearranged so that they occupied less space. The high mobility of the fine-grained materials 

ejected from the cracks suggests 

that they were liquefied spontaneously by the ground motion. 

Terzaghi (1950, p. 100) describes 

spontaneous liquefaction as the 

transformation of fine sand or 

coarse silt into a liquid state. 

Similar mechanisms of formation have been postulated for 

earthquake-induced ground cracks 

in South Carolina (Dutton, 1889, 

p. 267-268), in India (Oldham, 

1899, p. 88-92), in south-central 

United States (Fuller, 1912, p. 

ALASKA EARTHQUAKE, MARCH 27, 1964 

57), and in Japan (Imamura, 

1937, p. 75). 

DIFFERENTIAL VERTICAL COMPACTION 

Without detailed data it is difficult to determine the degree to 

which differential vertical compaction contributed to the formation of ground cracks throughout 

the area ; nevertheless, in certain 

areas this mechanism appears to 

have been dominant in their formation. 

In a typical bedrock-confined 

valley underlain by unconsolidated deposits, the 1naterials are 

much thinner along the margins 

of the valley wall than in the center of the valley. Where this condition exists and where the deposits are susceptible to vertical 

compaction, the materials in the 

center of the valley subside more 

than the materials along the valley 

walls because they are thicker. 

Consequently, ground cracks form 

generally near and parallel to the 

valley wall. Ground cracks such 

as these were observed along the 

eastern margin of the outwash 

apron of Tazlina Glacier and locally along the eastern margin of 

the outwash apron of Nelchina 

Glacier. Lateral variation in the 

texture and in void ratios of the 

unconsolidated deposits also can 

cause differential compaction. 

The broad cambering of the surface of the Nelchina River delta 

(fig. 15) and the concentration of 

ground cracks along and parallel 

to the hingeline (fig. 16) can be explained by differential vertical 

compaction· caused by lateral variation in the thickness of unconsolidated deposits. 

The wedge-shaped body of deltaic deposits was laid down over 

the lip of a valley wall, and the 

thicker deposits toward the front 

of the delta were compacted more 

than those toward the apex. The 

hingeline formed above and parallel to the lip of the buried valley 

wall-under conditions similar to 

those depicted in figure 20, section 0. 

SNOWSLIDES, ROCKSLIDES, 

AND AVALANCHES 

Within the area, snowslides, 

rockslides, and avalanches were restricted to the mountains sur~ 

rounding the Copper River Basin. 

They were especially numerous in 

the Chugach Mountains which are 

closest to the epicenter of the earthquake. Many glaciers emanate 

from an extensive icefield in the 

higher reaches of these rugged 

mountains. 

The remoteness of this vast 

mountainous region made it impractical to make a comprehensive 

study of the slides. However, reconnaissance flights over the area, 

reports of slides along the Richardson Highway where it crosses 

the Chugach Mountains, and 

study of postearthquake aerial 

photographs of the area indicate 

that slide activity was much 

greater than that in· past years 

when no earthquakes occurred. 

The large amount of snow and 

rock debris that has cascaded onto 

the icefield and glaciers, and, probably even more important, the 

overall disturbance to the icefield 

will affect the regimen of the glaciers emanating from it. According to Tarr and Martin (1912, p. 

51-61), several glaciers in the 

Yakutat area advanced abnormally after the Yakutat earthquake of 1899 because of earthquake-induced changes in the 

regimen of the glaciers. If their 

hypothesis is true, it is not unreasonable to expect that some of the 

glaciers in the Chugach Mountains 

will advance an abnormal amount 

within the next few years. 
EFFECTS IN THE COPPER RIVER BASIN AREA E25 

EFFECTS OF THE EARTHQUAKE ON MANMADE STRUCTURES 

DAMAGE TO BUILDINGS 

AND ASSOCIATED STRUCTURES 

The greatest amount of damage 

to buildings, which were mostly of 

wood-frame or log construction, 

occurred within the southern half 

of the area, primarily because of 

proximity to the epicenter of the 

earthquake. Within this part of 

the area, breakage of fragile items 

inside buildings was widespread. 

However, major structural damage to buildings was restricted to 

localities where the intensity and 

duration of ground motion was 

greatest. 

The following descriptions of 

damage to buildings and associated structures at various sites 

within the area were selected to 

give a representative picture of 

the range of damage: 

Sheep Mountain Inn, at mile 

113, Glenn Highway, is on the toe 

of an alluvial fan at the base of 

Sheep Mountain. Several ground 

cracks, oriented in a general east-

\test direction andoparalleling the 

t(')e of the fan, formed in the 

cleared area where the buildings 

were located. The ground movement caused severe damage to underground pipes, a small cabin was 

shaken off its foundation, and 

other buildings shifted position. 

A diesel engine was shaken off a 

concrete slab to which it was 

bolted. 

Tazlina Glacier Lodge, at mile 

156, Glenn Highway, had only 

minor damage. There was cori.siderable breakage inside, however, 

and most loose objects shifted 

position. 

Lee's Guide Service, a short distance north of the Glenn Highway 

at mile 158, was severly damaged. 

Several large crescent-shaped 

ground cracks formed in a cleared 

area adjacent and parallel to a 

lake. This area is underlain by 

gravelly silt. A small building 

was partly submerged in water 

when the ground upon which it 

was erected moved laterally toward the lake. When the ground 

cracks opened, water was ejected 

to the surface and flowed down the 

gentle slope to the lake. 

Glennallen, whose center is at 

mile 186, Glenn Highway, near the 

southern junction of the Glenn and 

Richardson Highways, is the 

largest community in the area. 

Brea,kage of fragile items inside 

buildings was widespread, but 

structural damage to buildings 

generally was not severe. 

A 5-unit motel, a barracks-type 

building, and a trailer house were 

shaken oft' their foundations. The 

foundation of the elementary 

school building also was severely 

damaged. S ever a 1 relatively 

small ground cracks formed in 

cleared areas and locally damaged 

structures. At the Copper Valley 

Electric Co. station, damage to 

the plant foundation, flooring, and 

equipment caused a power disruption for a little more than 4 hours 

while repairs were being made and 

generating equipment was being 

checked. The Glennallen Road 

Camp of the Alaskl} Department 

of Highways, the largest installation in GlennaTien, sustained damage to underground sewers, steam 

and water lines, well casings, windows, and a boiler. 

Gulkana Airfield, at mile 120, 

Richardson Highway, received 

only minor damage, even to fragile 

items inside buildings. A few 

small cracks formed in a paved 

runway and in roads, and a water 

pipe broke under one house. 

Chistochina Lodge, at mile 238, 

Glenn Highway, had no significant damage; even glasses on a 

shelf did not tip over. 

Tsina Lodge, at mile 34.5, Richardson Highway, in the southern 

part of the area of study had no 

major structural damage. However, a few fragile items inside the 

building were broken, and many 

loose items were moved. 

Tonsina Lodge, at mile 79, Richardson Highway, had minor structural damage; a fireplace and 2 

chimneys were cracked severely, 

windows were broken, walls 

cracked, and some differential settlement o c c u r r e d. Numerous 

fragile items inside the building 

were broken. 

DAMAGE TO HIGHWAYS 

AND BRIDGES 

Along the Glenn Highway from 

the Matanuska Glacier at the western edge of the area of study to 

the junction of the Glenn and 

Richardson H i g h w a y s near 

Glennallen, several small cracks 

formed in the pavement, and at a 

few places minor slumping of 

roadcuts occurred. The majority 

of these cracks were less than 6 

inches wide, and no major differential movement took place. From 

the junction north along the Glenn 

Highway, only a few small cracks 

formed in the pavement-none 

that required major repair. 
E26 

No damage was reported along 

the Lake Louise Road which extends from about mile 160 on the 

Glenn Highway to the southern 

end of Lake Louise, a distance of 

19 miles. 

Along the Richardson Highway, however, serious road damage occurred at several places between mile 27 near the southern 

edge of the area of study and mile 

91 near the junction of the Richardson and Edgerton Highways. 

A large crack formed in the roadway at mile 28 near Worthington 

Glacier, and severe road damage 

occurred along a 22-mile segment 

between mile 64, 1 mile south of 

the Little Tonsina · River bridge, 

and mile 86 near the Rock Creek 

bridge. Cracks as wide as 8 inches 

formed in the pavement, and 30-

to 50-foot segments of the roadbed were moved differentially (fig. 

21) . This differential movement 

was caused by Jandsliding which 

occurred in unconsolidated deposits on steep s~opes near the highway. The Little Tonsina River 

bridge also was damaged primarily by this landsliding (fig. 22). 

At mile 79.8 the slump of a long 

segment of the roadbed on a sidehill cut restricted vehicles to oneway traffic. At mile 86.1 just 

north of Rock Creek a small crack 

formed in an abandoned section of 

road, and therefore, the feature 

was we11 preserved. Because of 

the granular nature of the underlying materials and because of the 

high ground-water table, the 

earthquake-induced ground motion caused silt and fine sand ' along with water, to be ejected 

from the crack onto the road surface (fig. 23). Only a few small 

cracks formed in the pavement and 

road fill along the Richardson 

Highway north of mile 91. 

ALASKA EARTHQUAKE, MARCH 27, 1964 

21.-View, to the southeast, showing· the pavement surface of the Richardson 

Highway just south of the Little Tonsina River bridge at mile 65. Note the 8-inch 

horW:ontal offset of the centerline; vertical displacement is as much as 3 inches. 

22.-Landslide movement on a hillside approximately two-tenths of a III'ile away 

caused the Little Tonsina River bridge to be shoved from the right to the left. 

Minor slumping oc.C'UITed in road fill to the left of the bridge. Immediately after 

the earthquak;e the pavement was buckled more than 3 feet high at the left end 

of the bridge. 
EFFECTS IN THE COPPER RIVER BASIN AREA :E27 

23.-Small crack across abandoned section of road on a low gravel terrace adjacent 

to Rock Creek at mile 86.1, Richardson Highway. Note the fine sand and silt along 

both sides of the crack. 

Algermissen, S. T., 1965, Prince Wil'liam 

Sound, Alaska earthquake of March 

28, 1964, and aftershock sequence 

[abs.] : Geol. Soc. America Spec. 

Paper 82, p. 2. 

Andreason, G. E., Grantz, Arthur, Zietz, 

Isidore, and Barnes, D. F., 1964, 

Geologic interpretation of magnetic 

and gravity data in the Copper 

River Basin, Alaska: U.S. Geol. 

Survey Prof. Paper 316-H, p. 135-

153, pls. 23, 24. 

Berg, Eduard, 1&64, The Alaskan earthquake of March 1964-a review : 

Alaska Univ., Geophys. Inst. Ann. 

Rept. 1963- 64, p. 69-82. 

Coulter, H. W., and Coulter, E. B., 1962, 

Preliminary geologic map of the 

Valdez-Tiekel belt, Alaska: U.S. 

Geol. Survey Misc. Geol. Inv. Map 

I-356, scale 1: 96,000. 

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Davis, T. N., and Sanders, N. K., Alaska 

earthquake of July 10, 1958--Intensity distribution and field investigation of northern epicentral region : 

Seismol. Soc. America Bull., v. 50, 

no. 2, p. 221-252. 

Dutton; C. E., 1889, The Charleston 

earthquake of August 31, 1886: U.S. 

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203-528. 

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the new seismology: New York, 

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Eiby, G. A., 1957, A'bout earthquakes: 

New York, Harper & Bros., 168 p. 

Ferrians, 0. J., Jr., 1965, Permafrost 

map of Alaska: U.S. Geol. Survey 

Misc. Geol. Inv. Map I-445, scale 

1 : 2,500,000. 

Fuller, M. L., 1912, The New Madrid 

earthquake: U.S. Geol. Survey 

Bull. 494, 119 p. 

Snowslides covered the Richardson Highway near mile 38, mile 

39, and mile 42, and a rockslide 

blocked the road near mile 44; a 

large snowslide near mile 50 

dammed the Tiekel River, and because of the danger of flooding the 

highway, explosives were used to 

blast a channel in the slide. Ice 

jams on the Tonsina River near 

mile 75 and mile 78.5 caused the 

river to rise and to erode highway 

fill near mile 76 and mile 77; explosives were used to remedy this 

condition also. Between mile 66 

and mile 73, accelerated surface 

drainage from the steep mountain 

slope paralleling the highway on 

the east caused large icings to form 

on the highway. 

The Edgerton Highway was 

damaged very little, except for a 

200-foot landslide on the Lower 

Tonsina Hill, a short distance 

north of Lower Tonsina. The 

Lower Tonsina River bridge, 

which was shifted about 6 inches to 

the southeast, sustained considerable structural damage. 

Grantz, Arthur, Plafker, George, and 

Kachadoorian, Reuben, 1964, 

Alaska's Good Friday earthquake, 

March 27, 1964, a preliminary 

geologic evaluation: U.S. Geol. Survey Circ. 491, 35 p. 

Gutenberg, Beno, 1956, Effects of ground 

on shaking in earthquakes : Am. 

Geophys. Union Trans., v. 37, no. 6, 

p. 757-760. 

- - -1957, E::Iects of ground on earthquake motion : Seismol. Soc. America Bull., v. 47, no. 3, p. 221-250. 

Gutenberg, B., and Benioff, H., 1939, 

Waves and currents recorded by 

electromagnetic barographs: AM. 

Meteorol. Soc. Bull., v. 20, p. 421-

426. 

Imamura, Akitune, 1937, Theoretical 

and applied seismology : Tokyo, 

Maruzen Co., 358 p. 
E28 

India Geological Survey Officers, and 

Roy, S. C., 1939, The Bihar-Nepal 

earthquake of 1934: India Geol. 

Survey Mem., v. 73, 391 p. 

Jones, J. C., 1915, The Pleasant Valley, 

Nevada earthquake of October 2, 

1915 : Seismol. Soc. America Bull., 

v. 5, p. 190- 205. 

Karlstrom, T. N. V., Coulter, H. W., 

Fernald, A. T., Williams, J. R., Hopkins, D. M., Pewe, T. L., Drewes, 

Harold, Muller, E. H., and Condon, 

W. H., 1964, Surficial geology of 

Alaska: U.S. Geol. Survey Misc. 

GeO'l. Inv. Map I--357, scale 

1 : 1,584,000. 

Kingdom-Wal'd, F., 1951, Notes on the 

Assam earthquake: Nature, v. 167, 

p .. 130-131. 

---1953, The Assam earthquake of 

1950: Geog. Jour., v. 119, pt. 2, 

p.169-182. 

Knott, C. G., 1908, The physics of earthquake phenomena: Oxford, Clarendon Press, 283 p. 

ALASKA EARTHQUAKE, MARCH 27, 1964 

Leet, L. D., and Leet, Florence, 1964, 

Earthquake---Oiscoveries in seismology: New York, Dell Publishing 

Co., 224 p. 

Miller, D. J., Payne, T. G., and Gryc, 

George, 1959, Geology of possible 

petroleum provinces in Alaska : 

U.S. Geol. Survey Bull. 1094, 131 

p., 6 pis. 

Oldham, R. D., 1899, Report on the great 

earthquake of 12th June 1897: 

India Geol. Survey Mem., v. 49, 

379p. 

Plafker, George, 1965, Tectonic deformation associated with the 1964 

Alaska earthquake: Science, v. 148, 

no. 3678, p. 1675-1687. 

Press, Frank, and Jackson, David, 1965, 

Alaska earthquake, 27 March 

1964-vertical extent of faulting 

and elastic strain energy release: 

Science, v. 147, no. 3660, p. 867-868. 

Richter, C. F., 1958, Elementary seismology : San Francisco, Calif., W. 

H. Freeman and Co., 768 p. 

State Earthquake Investigation Commission, 1908, The California earthquake of April 18, 1906: Carnegie 

Inst. Washington, v. 1, 451 p. 

Tarr, R. S., and Martin, L.M., 1912, The 

earthquake of Yakutat Bay, Alaska, in September, 1899: U.S. Geol. 

Survey Prof. Paper 69, 135 p. 

Terzaghi, Karl, 1950, Mechanism of 

landslides, in Application of geology to engineering practice (Berkey 

volume) : New York, Geol. Soc. 

America, p. 83-123. 

Thompson, A., 1929, Earthquake sound's 

heard at great distances: Nature, 

v. 124, p. 687-688. 

U.S. Coast and Geodetic Survey, 1964, 

Prince William Sound, Alaskan 

earthquakes, March-April 1964 : 

U.S. Coast and Good. Survey, Seismology Div. Prelim. Rept., 83 p. 

U.S. GOVERNMENT PRINTING OFFICE: 1966 0-221~93