EARTHQUAKES AND RELATED 

CATASTROPHIC EVENTS, 

ISLAND OF HAWAII, 

NOVEMBER 29,1975

A Preliminary Report

GEOLOGICAL SURVEY CIRCULAR 74O
Earthquake and Related Catastropic Events, 

Island of Hawaii, November 29, 1975: A 

Preliminary Report

By Robert I. Tilling, Robert Y. Koyanagi, 

Peter W. Lipman, John P. Lockwood, James G. 

Moore, and Donald A. Swanson

GEOLOGICAL SURVEY CIRCULAR 740

1976
United States Department of the Interior

THOMAS S. KLEPPE, Secretary

Geological Survey

V. E. McKelvey, Director

Library of Congress Cataloging in Publication Data

Tilling, Robert I.

Earthquake and related catastrophic events, Island of Hawaii, November 29 1973.

(Geological Survey Circular 740)

Bibliography: p. 32-33.

Supt.ofDocs.no. I 19.4/2:740

1. Hawaii-Earthquake, 1975 2. Earth movements-Hawaii. 3. Hawaii-Tsunami, 1975.

I. Tilling, Robert I. II. Title. III. Series: United States Geological Survey Circular 740. 

QE75.C5 no. 740[QE535.2.U6] 557.3'08s[551.2'2'099691] 76-608262

Free on application to Branch of Distribution, U.S. Geological Survey, 1200 South Eads Street, Arlington, VA 22202
CONTENTS

Page

Abstract _______________________________________________________________________ 1

Narrative _____________________________________________________________________ 1

The earthquake ______________________________________________________________________ 3

Structural damage ________________________________________________________________ 3

Earthquakes probably related to main earthquake _______________________________ 4

The tsunami __________________________________________________________________ 9

C hronology ____ _ ______________ _ _______________________________________________ 9

Characteristics ________________________________________________________________ 14

The eruption ___________________________________________________________________ 15

Ground movements ____________________________________________________________ 17

Subsidence of the south coast _______________________________________________ 17

Faulting in the Hilina system ____________________________________________________ 19

Postearthquake adjustments ________________________________________________________ 21

Landslides and ground cracks ________________________ ______________________ 21

Deformation related to magma movement __________________________----__-----_ 26

Cause of earthquake and ground movements ___________________ _________________ 28

Comparison with 1868 events __________________________________________________ 29

Lessons for the future _______________________________________________________ 30

Acknowledgments__________________________________________________________ 32

Suggested reading ______________________________________________________________ 33

ILLUSTRATIONS

Page

FIGURE 1. Index map ________________________________________________________________________________________ 2

2. Epicenters of November 29 earthquake ______________________________________--------__-------_-------- 4

3. Photographs showing earthquake damage _________________________________________________________ 7

4. Preliminary isoseismal map of Hawaii _____________ _________ ___________________________ 8

5. Curve of daily frequency of earthquakes________________---___________-_-----__-------- ________-__----_ 9

6. Map showing epicentral distribution of moderate to large earthquakes __________________________________ 10

7. Graph showing maximum heights of the two locally generated tsunamis ___________ _ ______ _ ________ 11

8. Photographs showing tsunami damage _______________________________________________________________ 12

9. Photograph of part of keawe tree ________ ________________________________________________ 14

10. Plot of approximate tsunami arrival times____________----________--------------------_--------__------- 16

11. Plot of height of tsunamis for five major events 1868-1975 _________________ _______________ 17

12. Sketch map of recent vents and lava flows______________________________________________________ 18

13. Photograph of lava fountains on floor of Kilauea Caldera ________________________________________________ 19

14. Oblique aerial view toward southwest of floor of Kilauea Caldera ________________-_----_____----___---- 20

15. Photographs showing preearthquake and postearthquake views of coast of Halape and Keauhou Landing __ 22

16. Map showing zones of major faulting __________________________________________________________________ 24

17. Profile showing amount of subsidence at points along the coastline ________________________________ 24

18. Postearthquake and preearthquake aerial views showing Hilina fault system ____________________________ 25

19. Photograph showing vertical offset of about 1.5 m along new fault ___________________---_________------_ 26

20. Photographs showing ground cracking and landslides in Hawaii Volcanoes National Park _______________ 27

21. Photograph showing large crack in Crater Rim Road________________________________--______---------_ 28

22. Photograph showing small compressional chevron fold across road __________________________________ 28

23. Photograph showing collapse offsetting center line, Chain of Craters Road__ _______________ 29

24. Graph showing changes in tilt May-December 1975 recorded on tiltmeter ______________________________ 30

25. Oblique physiographic map of the south half of the island of Hawaii _____________------__ ____________ 31

III
TABLES

Page

TABLE 1. Intensities and description of damage from the magnitude 7.2 earthquake, November 29, 1975 _________ 5

2. Modified Mercalli scale (1956 version) of earthquake intensity __________________-________ 6

3. Tsunami characteristics as recorded by some Pacific tide gages, supplemented by visual observations ___ 15

Cover photographs by UPI, David Shapiro, Star-Bulletin, and Boone Morrison.

IV
Earthquake and Related Catastrophic Events

Island of Hawaii, November 29, 1975:

A preliminary report

By Robert I. Tilling, Robert Y. Koyanagi,

Peter W. Lipman, John P. Lockwood, James G. Moore,

and Donald W. Swanson

ABSTRACT

The largest earthquake in over a century magnitude 7.2 

on the Richter Scale struck Hawaii the morning of 

November 29, 1975, at 0448. It was centered about 5 km beneath the Kalapana area on the southeastern coast of the 

island (lat 19°20.1' N., long 155°01.4' W.). The earthquake 

was preceded by numerous foreshocks, the largest of which 

was a 5.7-magnitude jolt at 0336 the same morning, and was 

accompanied, or closely followed, by a tsunami (seismic sea 

wave), massive ground movements, hundreds of aftershocks, 

and a volcanic eruption.

The tsunami reached a height of 12.2-14.6 m above sea level 

on the southeastern coast about 25 km west of the earthquake 

center, elsewhere generally 8 m or less. The south flank of 

Kilauea Volcano, which forms the southeastern part of the 

island, was deformed by dislocations along old and new faults 

along a 25-km long zone. Downward and seaward fault displacements resulted in widespread subsidence, locally as 

much as 3.5 m, leaving coconut palms standing in the sea and 

nearly submerging a small, near-shore island. A brief, smallvolume volcanic eruption, triggered by the earthquake and 

associated ground movements occurred at Kilauea's summit 

about three-quarters of an hour later. The earthquake, together with the tsunami it generated, locally caused severe 

property damage in the southeastern part of the island; the 

tsunami also caused two deaths. Damage from the earthquake 

and related catastrophic events is estimated by the Hawaii 

Civil Defense Agency at about $4.1 million.

The 1975 Kalapana earthquake and accompanying events 

represent the latest events in a recurring pattern of behavior 

for Kilauea. A large earthquake of about the same magnitude, 

tsunami, subsidence, and eruption occurred at Kilauea in 

1868, and a less powerful earthquake and similar related 

processes are believed to have occurred in 1823. Indeed, the 

geologic evidence suggests that such events have been repeated many times in Kilauea's past and will continue. The 

1975 events serve as a critical, though tragic, reminder of the 

dynamic nature of the volcano and point up the need for careful land-use planning and adequate building codes to 

minimize damage and loss of life from similar events in the 

future.

Detailed scientific study of the cause and effects of the 

November 29, 1975, event will take many months. This report 

summarizes information available in February 1976.

NARRATIVE

At 03361 on Saturday, November 29, 1975, a 

sharp earthquake, foreshock to the largest in over 

a century, woke most residents on the island of 

Hawaii, including 32 people camped near the 

beach at Halape, a coconut palm grove on the 

southeastern coast (fig. 1). This quake, 5.7 on the 

Richter Scale, was centered about 8 km beneath 

the south flank of Kilauea Volcano, approximately 5 km inland of Kamoamoa (fig. I).2 In the 

dim predawn light, the campers at Halape near 

the base of 320 m-high Puu Kapukapu (Forbidden 

Hill) saw dust clouds rising from rockfalls that 

the earthquake sent crashing down its steep face. 

Instinctively, some of the campers moved their 

sleeping bags away from the area of the falling 

rocks, closer to the beach. One young boy told his 

father that he felt something bad was going to 

happen and that he wanted to leave. He was reassured, and most of the campers went back to 

sleep.

About an hour later, at 0448, a second, much 

stronger, earthquake struck the island. Unlike 

the earlier one, this quake, centered about 5 km 

beneath Kilauea's south flank near Kamoamoa, 

did not quickly subside in intensity. The violent 

ground shaking caused electrical power outages 

in many parts of the island, and seismographs at 

the Hawaiian Volcano Observatory went off 

scale. Scientists at more distant locations, as at 

stations in North America, Japan, and New Zealand, where seismographs did not go off scale, 

later calculated a Richter magnitude of 7.2. The

'All times Hawaiian standard time (H.s.t.I unless otherwise noted. 

2All measurements given in metric units.
last previous earthquake of similar magnitude 

occurred in 1868.

At Halape, about 25 km west of the epicenter, 

the campers were able to stand during initial 

periods of the violent shaking but were soon 

thrown to the ground if they did not cling to trees 

or large rocks for support. A deafening roar rose 

from Puu Kapukapu as numerous rockfalls rumbled down its south cliff face. Many campers, 

frightened by the noise, moved still closer to the 

beach, away from the falling rocks. Some thought 

about the possibility of a tsunami and ran toward

the beach to check the sea. Their flashlights 

shone on a slowly but noticeably rising sea. 

Within a minute or so, sea level began to rise 

faster, causing the campers to run back toward 

the rockfalls at the base of Puu Kapukapu. The 

rising water, now a breaking, surging wave, 

knocked many of the campers off their feet, 

briefly submerging some as they fled for higher 

ground. They had barely time to catch their 

breath before a second wave struck, far more turbulent and higher than the first, carrying every 

loose object in its path as far as 100 m inland.

POINT

KALUE ^ ~«APUA POINT 

KEAUHOU LANDING

/

_ WAIOALA SPRING 

KAMEHAME HILL 

PUNALUU

30Km 

I

FIGURE 1. Index map of the island of Hawaii showing the location of the Hawaiian Volcano Observatory (HVO) and other

places on the island affected by the events of November 29, 1975.
Trees, debris from the Halape shelters, rocks, 

horses, and people were washed into a large, preexisting crack in the ground, 5-7 m deep and 10 m 

or more wide, churned by the surging wave. One 

survivor said he felt like he was "inside a washing 

machine." Several smaller waves repeatedly 

washed over the exhausted victims stranded in 

the crack. One person was drowned or battered to 

death during the terrifying ordeal; another was 

swept out to sea and is presumed dead. Nineteen 

people were injured at Halape; seven required 

hospitalization. Four of ten horses were lost.

The large waves that wreaked havoc at Halape 

were caused by sudden nearby earth movements. 

These waves reached Halape within 30 seconds 

after the strongest shaking had ended, spreading 

outward from their source at speeds of several 

hundred kilometers per hour.

At Punaluu (fig. I), 30 km southwest of Halape, 

the disastrous quake woke the several families 

camped near the beach and others sleeping in 

nearby houses, but few suspected that a tsunami 

was moving swiftly toward them. Sea level began 

rising rapidly within a few minutes after the 

earthquake, forcing campers and residents to 

wade quickly to higher ground. The largest wave 

arrived about 10 minutes later, destroying seven 

homes and two vehicles and causing interior damage of nearly $1 million as it swept through a 

large beachfront restaurant and gift shop; the 

structures remained standing. No injuries were 

reported. Farther southwest, at Honuapo, the 

spreading tsunami damaged a fishing pier, destroyed park facilities and a warehouse, then continued to Kaalualu Bay, 21 km southwest of 

Punaluu, where it damaged vehicles, ravaged a 

campsite, and badly frightened seven campers.

In Hilo (fig. 1), the main population center on 

the island, the major earthquake toppled some 

chimneys, damaged structures, shattered windows, and shook merchandise from shelves. Civil 

Defense authorities sounded a tsunami watch, 

and much of the low-lying coastal area was 

evacuated. At about 0510, when the water level 

dropped with the recession of the first tsunami, 

crew members of the U.S.S. Cape Small, a Coast 

Guard cutter moored in Radio Bay in Hilo Harbor, watched their ship settle to the muddy bottom and begin to list to one side. A series of waves 

surged in and out of the bay at approximately 

15-minute intervals, smashing some small boats 

and washing others onto docks; four boats were

sunk and three damaged. One of the waves 

washed a car from the pier into the harbor; 

another threw a man from his boat onto the pier, 

then washed him back into the water and onto his 

boat as the wave receded.

At 0532 lava began to fountain from a 500-mlong fissure on the floor of Kilauea Caldera and 

continued to erupt sporadically until about 2200. 

No injuries or property damage resulted from this 

small eruption, but the earthquake and tsunami 

had already taken a heavy toll in Hawaii.

THE EARTHQUAKE

Data from seismometers operated by the 

Hawaiian Volcano Observatory (HVO) placed the 

7.2-magnitude earthquake about 5 km westsouthwest of Kalapana on Hawaii's southeastern 

coast (lat 19°20.1' N., long 155°01.4'W.) at a 

depth of about 5 km (fig. 2). The earthquake was 

strong enough to be felt on the neighbor island of 

Maui and on Oahu, more than 400 km from the 

epicenter.

During and immediately after the earthquake, 

intense bursts, glows, or flashes of white to bluish light, lasting from a few seconds to about a 

minute, were observed by a number of people, including some of the campers at Halape. Such 

"earthquake lights" have been observed before, 

during, and after major earthquakes, mostly in 

Japan and California. Although there is no generally accepted scientific explanation for their occurrence, earthquake lights apparently result 

from earthquake-induced oscillations or distortions of the atmosphere.

STRUCTURAL DAMAGE

The main earthquake caused structural damage estimated at about $2.7 million. A preliminary survey conducted by various governmental 

agencies showed minor to moderate damage to 5 

churches (4 in Hilo, 1 in Opihikao), 11 commercial buildings (10 in Hilo, 1 in Mountain View), 

and 80 homes (51 in Hilo, 23 in Puna, 2 in 

Hamakua, 3 in Ka'u, and 1 in Kona). Five poorly 

constructed or old houses were reported completely demolished (4 in Hilo, 1 in Ka'u) (fig. 3).

All available sources of information were used 

to estimate relative intensities of the November 

29 earthquake in different parts of the island (table 1). Earthquake intensity is defined in terms of 

observed physical effects and damage related to
HVO

M7.2 MAIN SHOCK, 11-29-75

 AFTERSHOCKS, 11-29-75

O SELECTED AFTERSHOCKS 11-30-75 TO 12-14-75

3? KILAUEA SOUTH FLANK

10

_L

20 30 Km

FIGURE 2. Epicenters of the November 29, 1975, magnitude-7.2 earthquake, its largest foreshock (magnitude 5.7), and 

selected larger aftershocks. The fault systems and rift zones are as shown in figure 1.

local ground shaking (table 2); it differs from 

magnitude, which is calculated from data obtained by seismic instruments. Earthquakeintensity variations may be contoured to produce 

isoseismal maps commonly used by seismologists 

and civil engineers to assess patterns of earthquake damage and effects.

As much of Hawaii is unpopulated, direct observations of ground shaking and its effects are 

not known for large areas; for this reason, the 

intensity map for the main earthquake (fig. 4) is 

based on irregularly distributed, statistically inadequate, data. Nonetheless, observations do 

show most buildings within 20 km of the earthquake epicenter sustained no significant structural damage from the ground shaking, whereas 

buildings in Hilo and at the summit region of 

Kilauea Volcano, far from the epicenter, showed

extensive damage. The building at the Wahaula 

Visitor Center of Hawaii Volcanoes National 

Park, located almost directly at the earthquake 

epicenter, was virtually undamaged. The apparent offset of the zone of maximum damage (intensity VII-VIII; fig. 4) from the epicentral region 

poses an enigma for which there are no ready 

solutions at present.

EARTHQUAKES PROBABLY RELATED 

TO MAIN EARTHQUAKE

The general level of seismicity on the south 

flank of Kilauea increased somewhat during the 

month preceding the main earthquake (fig. 5), 

and several of the larger (magnitude 4-5) shocks 

were felt islandwide. A number of these earthquakes, which in hindsight may be called foreshocks, were located near the Kalapana area. The
TABLE 1. Intensities and description of damage from the magnitude 7.2 earthquake, November 29, 1975

[Intensities are based on the Modified Mercalli Scale, table 2]

District (towns, villagesi

Hilo

Intensity

V-VIII

Puna (Volcano, Hawaii 

Volcanoes National Park)

VII-VIII

Puna (Kalapana)

(Kapoho) 

(Kurtistown)

(Opihikao) 

(Pahoa)

(Glenwood) 

(Mountain View)

(Hawaiian Paradise Park) 

(Black Sands Subdivision)

(Hawaiian Beaches)

Description of damage

Extensive damage in downtown area. Minor 

cracks in road, water pipes, concrete walls 

and floors, plaster. Minor cracks and floprto-wall separations a few millimeters wide 

and bowing of the walls were observed in 

steel-reinforced concrete structures at the 

hospital, several schools, and libraries. 

Some of these buildings 5 to 10 mm vertical 

drops in some floor sections. Churches in 

Hilo reported damage to a pipe organ, cracks 

in hollow tile blocks, breaks in a swimming 

pool, and water lines. Hotels, apartments, 

and business buildings suffered structural 

and equipment damage. Shelved items in 

markets fell or tumbled over. Fifty-one 

home owners in Hilo reported loss due to 

broken water pipes, windows, plate glass, 

water gutters; cracks in concrete walls and 

steps; cupboards torn away from walls and 

breakage of chinaware; collapse of stone 

walls and fences; plumbing damage and 

cesspool cave-ins; house and garage shifting 

from foundation; doors and doorways distorted; leaks in roofs; minor ground cracks, 

chipping of ceramic tile floors; collapse of 

stairways; cracking or crumbling of brick 

fireplace chimneys.

Extensive ground cracking caused heavy road 

damage in the National Park. On the 

Crater Rim Road, damage was reported in 

Waldron Ledge, Kilauea Military Camp, 

Halemaumau, and Keanakakoi sections. 

Damage was noted on the Chain of Craters, 

Ainahou, and Hilina Pali Roads. A water 

tank at the Youth Conservation Corps and 

Kipuka Nene was damaged. Waterlines in 

several areas broke. Fireplace chimneys at 

Kilauea Military Camp and at a residential 

home in Volcano collapsed. About three 

wooden water tanks were destroyed, and 

several others were partially damaged at 

Volcano. At the Volcano Observatory, violent ground motion lasted about half a minute, many loose objects moved or turned 

over, sounds were heard from rockfalls in 

crater and water sloshing in water tank.

A wood frame house shifted 1 m from foundation. One water tank damaged. Many small 

road cracks. Residents report strong shaking; that loose objects fell off shelves.

Minor cracks and small rockfalls from walls of 

cinder cones.

Damage in seven residential homes cracked 

concrete steps, house and garage moved 

from foundation, 10-cm wall separation, roof 

separation, chinaware broken from falling 

out of cupboards. Rock wall damaged.

Two water tanks at a church destroyed.

Three homes moved from foundation. Other 

damage included a broken waterline, collapsed water tank, and toolshed.

Loose objects fell off shelves, water splashed 

out of fish bowl.

Floor of water tank cracked; plexiglass 

cracked; television set shifted off stand and 

fell to the floor; rock wall damaged.

One house shifted off foundation; cabinets toppled off walls.

Damage reports from two homes. One house 

dropped 7.5 cm; walls cracked, loose objects 

fell. At other residence, water tank fell and 

house beams cracked.

A garage concrete slab cracked.
TABLE 1. Intensities and description of damage from the magnitude 7.2 earthquake, November 29, 1975 Continued

District (towns, villages I

Kau

Kona 

Hamakua

Kohala

Intensity Description of damage

IV-VII In Naalehu, foundation to one ranch house

cracked and roof damaged. One homeowner 

in Pahala reported doors distorted, house 

moved from concrete foundation, furniture 

and stereo fell.

IV Loose objects fell off shelves; strong shaking,

rockfalls in Kealakekua.

IV-VI Landslides on coast road at Laupahoehoe and

Honomu; loose objects fell off shelves. Heavy 

rolling ground motion.

HI-IV Some loose objects moved; shaking felt by

many people.

largest foreshock at 0336, 5.7 magnitude, occurred about 4 km northwest of, and 72 minutes 

before, the 7.2-magnitude quake (fig. 2).

A thousand or more earthquakes per day (fig: 

5), some felt and heard by local residents, continued to shake the region for 2 weeks following 

the November 29 event. These earthquakes, 

termed aftershocks, were distributed primarily 

north of the inland margin of the Hilina fault 

system west of the epicenter of the main earthquake. Most occurred at depths of 5-7 km. During 

the same time, the frequency of earthquakes increased beneath the southwest flank of Kilauea, 

suggesting possible migration of magma into the 

southwest rift zone as the summit area deflated 

after the brief summit eruption. Aftershock activity continues (mid-February 1976), though at a 

steadily declining level. Extrapolation of the 

present rate of diminution of activity (fig. 4) and 

comparison with previous well-documented major 

earthquakes in Hawaii suggest that aftershocks 

will continue into the late summer of 1976, when 

seismic activity on the south flank may return to 

its normal level, like that of August-October 

1975.

Studies of past seismicity beneath the south 

flank of Kilauea show some similarities of earlier 

events to the present activity. The largest earthTABLE 2. ModifiedMercalliScale (1956 version \ofearthquake 

intensity

[From Charles F. Richter, 1958, Elementary Seismology: San Francisco, W. H. 

Freeman and Co., 768 p. Annotated by Richter (CFRi]

I. Not felt. Marginal and long-period effects of large 

earthquakes.

II. Felt by persons at rest, on upper floors, or favorably 

placed.

III. Felt indoors. Hanging objects swing. Vibration like 

passing of light trucks. Duration estimated. May not 

be recognized as an earthquake.

IV. Hanging objects swing. Vibration like passing of heavy 

trucks; or sensation of a jolt like a heavy ball striking 

the walls. Standing motor cars rock. Windows, dishes, doors rattle. Glasses clink. Crockery clashes. In 

the upper range of IV wooden walls and frame creak.

TABLE 2. Modified Mercalli Scale (1956 version ) of earthquake 

intensity Continued

V. Felt outdoors; direction estimated. Sleepers wakened. 

Liquids disturbed, some spilled. Small unstable objects displaced or upset. Doors swing, close, open. 

Shutters, pictures move. Pendulum clocks stop, start, 

change rate.

VI. Felt by all. Many frightened and run outdoors. Persons 

walk unsteadily. Windows, dishes, glassware broken. 

Knickknacks, books, etc., off shelves. Pictures off 

walls. Furniture moved or overturned. Weak plaster 

and masonry D cracked. Small bells ring (church, 

school). Trees, bushes shaken (visibly, or heard to 

rustle CFR).

VII. Difficult to stand. Noticed by drivers of motor cars. 

Hanging objects quiver. Furniture broken. Damage 

to masonry D, including cracks. Weak chimneys broken at roof line. Fall of plaster, loose bricks, stones, 

tiles, cornices (also unbraced parapets and architectural ornaments CFR). Some cracks in masonry C. 

Waves on ponds; water turbid with mud. Small slides 

and caving in along sand or gravel banks. Large bells 

ring. Concrete irrigation ditches damaged.

VIII. Steering of motor cars affected. Damage to masonry C; 

partial collapse. Some damage to masonry B; none to 

masonry A. Fall of stucco and some masonry walls. 

Twisting, fall of chimneys, factory stacks, monuments, towers, elevated tanks. Frame houses moved 

on foundations if not bolted down; loose panel walls 

thrown out. Decayed piling broken off. Branches broken from trees. Changes in flow or temperature of 

springs and wells. Cracks in wet ground and on steep 

slopes.

IX. General panic. Masonry D destroyed; masonry C heavily damaged, sometimes with complete collapse; 

masonry B seriously damaged. (General damage to 

foundations CFR.) Frame structures, if not bolted, 

shifted off foundations. Frames racked. Serious damage to reservoirs. Underground pipes broken. Conspicuous cracks in ground. In alluviated areas sand 

and mud ejected, earthquake fountains, and craters.

X. Most masonry and frame structures and bridges destroyed. Serious damage to dams, dikes, embankments. Large landslides. Water thrown on banks of 

canals, rivers, lakes, etc. Sand and mud shifted horizontally on beaches and flat land. Rails bent slightly.

XI. Rails bent greatly. Underground pipelines completely 

out of service.

XII. Damage nearly total. Large rock masses displaced. 

Lines of sight and level distorted. Objects thrown into 

the air.
FIGURE 3. Damage caused by November 29, 1975, earthquake. A, Two children were trapped in this damaged home 

about 7 km north of Hilo. B, Spilled merchandise in Hilo supermarket. C. Collapsed chimney that fell through roof, 

dining room, Kilauea Military Camp, Hawaii Volcanoes National Park. D, Volunteers replace 300-lb granite headstone toppled by earthquake at churchyard, Kurtistown, 14 km south of Hilo. E, Fallen ceiling plaster and cinder 

blocks, Hilo High School. (Photographs: A, UPI; B, C, E, Larry Kadooka, Hawaii Tribune-Herald; D, George Abe, 

Hawaii Island Chamber of Commerce.)
35Km 

I

EARTHQUAKE

/ / EPICENTER 

I / VOLCANO, HVNP
quake to occur near Kalapana during this century was a 6.5-magnitude shock in March 1954. 

Unfortunately, the seismic network and coverage 

before 1955 was limited, and earthquake determinations were far less precise than at the present time. Nonetheless, some critical comparisons 

can be made.

The 6.5-magnitude earthquake on the morning 

of March 30, 1954, located about 4 km west of 

Kalapana, was preceded by a 6.0-magnitude 

foreshock nearly 2 hours before and a few 

kilometers inland (fig. 6). The main shock was 

followed by intense aftershock activity, probably 

clustered in an elongate belt along much the 

same part of the Hilina fault system as the aftershock area related to the 1975 earthquake (fig. 6). 

In the time between 1954 and 1975, several other 

moderate (magnitude 4-5) earthquakes within 

the Hilina fault system west of the main 1954 

earthquake were accompanied by aftershock activity. In each instance, if the principal earthquake was located in the eastern part of the 

Hilina fault system, the aftershock area was 

offset or elongate west of the main epicenter, 

whereas if the main earthquake originated in the 

central part of the fault system, the aftershock 

area was offset or elongate eastward.

From October 1961 until November 29, 1975, 

no earthquakes larger than magnitude 4.5 occurred in the Kalapana area. During this time, 

most earthquakes within the Hilina fault system 

occurred in a zone extending eastward from an 

area northwest of Apua Point nearly to Kalapana, and in the more recent activity (1971-74), 

in the western end of the system. No moderate or 

large earthquakes have struck the part of the 

Hilina system between Apua Point and Na Puu O 

Na Elemakule (fig. 6) for more than 20 years. It is 

significant that this part of the fault system is the 

area in which 1975 ground breakage was miniFIGURE 4. A preliminary isoseismal map of the island of 

Hawaii for the 7.2-magnitude earthquake, November 29, 

1975 (compiled from damage reports summarized in table 3 

and other sources). Intensities (III-VIII) are based on the 

Modified Mercalli Scale, 1956 version (table 2). Areas in 

Hilo, Volcano, and Hawaii Volcanoes National Park 

(HVNP) generally were most damaged (intensity VIII). Approximate population density of the island shown by dots; 

each small dot represents 100 people; larger dots represent 

principal towns containing from a few hundred to several 

thousands of people.

2

u IZ5O

ee 790 

u

£ 900

Daily frequency of 

Kilauea southeast flank 

earthquakes

FIGURE 5. Daily frequency of earthquakes within the south 

flank of Kilauea from August 1975 through mid-February 

1976. Most of these earthquakes were much too small to be 

felt.

mal. Equally significant, aftershock activity in 

Kilauea's south flank from 1950 to 1975 was restricted to a 6-km-wide belt bounded on the south 

by the northern edge of the Hilina fault system; 

the virtual absence of aftershock activity farther 

south (fig. 2) is not yet understood.

THE TSUNAMI

The tsunami was generated by sudden ground 

motion associated with the main earthquake. It 

produced one of the largest waves recorded in 

Hawaiian history and the only destructive one 

generated locally in the 20th century, killing two 

people and causing property damage of about $1.4 

million. Had the tsunami not expended much of 

its energy on the sparsely populated southeast 

coast of the island, it probably would have caused 

considerably more property damage, injuries, and 

deaths.

CHRONOLOGY

The 32 campers at Halape (fig. 1) were the first 

to experience the tsunami. The sea began slowly 

and quietly rising within 10-30 seconds after 

ground shaking had diminished. No withdrawal 

of water was observed before this initial rise. The 

rising water rapidly developed into a rushing 

wave, followed by at least two more large waves. 

The major part of the tsunami was over a scant 10 

minutes after it had begun, and the highest wave 

reached 14.6 m above the postsubmergence
KALAPANA

NA PUUQNA ELEMAKULE

, 1954 MAIN SHOCK 

\ M7.2 MAIN SHOCK. 11-29-75 

M5.7 FORESHOCK. 11-29-75

O M4.5to4.9 CRUSTAL EARTHQUAKES 1955-74 

& KILAUEA SOUTH FLANK

10 20 30 Km

ANNUAL FREQUENCY 1954-74

6.5

5.5

ID

< 4.5

1950 I960 

YEAR

1970

FIGURE 6. A, Epicentral distribution of moderate to large earthquakes beneath Kilauea's south flank, 1950 to 1974. 

Fault systems and rift zones as shown in figure 1. B, Distribution by time and magnitude (M) of earthquakes 

plotted in A. With gradual expansion and upgrading of HVO seismic network since 1954, the uncertainty in earthquake locations has improved from about 5-km radius of error to about 1-km radius of error or better.

shoreline (fig. 7). Observations at other places indicate that the tsunami consisted of five or more 

distinct waves.

The waves spread east and southwest from 

their source near Halape at approximately 300 

km per hour. At about 0508, the tsunami struck 

Hilo Bay, where the first effect was a 0.5-m rise of 

water, followed by a larger recession; the second 

and largest wave, about 2.5 m high, crested at 

approximately 0530. Moving southwest from its 

source, the tsunami struck Punaluu shortly before 0500; the first wave was relatively small, but 

the second surged several hundred meters inland 

and reached 5.5 m above sea level. The spreading 

tsunami damaged the park area at Honuapo 6 km 

to the southwest, rounded South Point, and

struck the highly developed west (Kona) coast of 

Hawaii at about 0515. At Keauhou Bay, some 

fishing boats were sunk and others damaged by a 

2.5-m wave that crested over the pier, crashed 

through a house, and left one fishing boat 

stranded on the dock. At Kailua-Kona, the wave 

crested at 2.1 m, piled debris against a newly 

completed hotel, sank one boat, and damaged 

three others (fig. 8).

Along the Kona Coast, the tsunami caused 

wide oscillations in sea level for more than an 

hour. At 0521, water receded 1.2-1.5 m at Napoopoo, at 0527 water receded 1.5-2.4 m at Kahaluu, 

and at 0528 water receded 2.4 m at Kailua; at 

0535 water rose at Maniui beach, at 0536 high 

waves were reported at Kahaluu, at 0545 the

10
SMALL, _ V>MAHUKONA

LAUPAHOEHOEtfSr 1.8, _

1.5, _

0.9, 1.5 VpKAWAIHAE 

1.5. __

HAWAII 

TSUNAMI HEIGHTS IN METERS

1975 1868

2.4 3.0

dash indicates no observations

V-5' -

\_>2.6, _

5-9.4, _

7.0, _ 

4.3-5.8, 6.1 

5.5, _ 

-3, _ 

2.1, _ 

6.1, 6.1

5OKm

3.4, _

FIGURE 7. Maximum heights of the two locally generated tsunamis (April 1868 and November 1975) on the shore of the 

island of Hawaii in historic time. All wave heights are given in meters relative to present, that is, postsubsidence, mean 

lower low water.

Kailua pier was under water, at 0650 water was 

over the Alii Drive roadway in Kailua, and at 

0658 wave action continued in Keauhou Bay.

The wave was recorded by tide gages throughout the Hawaiian islands and elsewhere (table 3), 

but did no serious damage west of the Island of 

Hawaii. At Hana, Maui, a fisherman, noting an 

unusual recession of water at about 0530, waded

out through the surf with a throw net before 

water rising neck-high drove him back. Tide 

gages on Oahu and Kauai registered the passage 

of the tsunami only a few centimeters high. Tide 

gages along the coast of California, Alaska, and 

some Pacific islands registered the tsunami 4-6 

hours later. The wave caused minor damage to 

floating dock facilities at Catalina Island off the 

California coast.

11
FIGURE 8. Damage caused by earthquake-related tsunami, November 29, 1975. A, Collapsed concrete finger pier, Wailoa 

River estuary, Hilo. B, Overturned boat, Wailoa River small-boat harbor. C, House shoved 25 m inland off its foundation, 

Punaluu, D, Foundation remains of a warehouse destroyed at Honuapo. E, Piano washed out of restaurant, Punaluu. F, 

Tables and chair (on branch) from restaurant deposited near pond, Punaluu. G, Demolished home, Punaluu. H, Car com12
 "fc

pletely turned around and smashed, Punaluu. 7, Powerboat washed onto dock, Keauhou Bay, Kona. (Photographs: A, B, 

Hugh Clark, Honolulu Advertiser; C, Paul Miyasaki, Hawaii Tribune-Herald; D, H, Andy Badig, Ka'u News; E, F, George 

Garcia, Kilauea Military Camp; G, David Shapiro, Star-Bulletin; I, Leigh Critchlow, Hawaii Tribune-Herald.)

13
CHARACTERISTICS

The tsunami reached its maximum height of 

14.6 m above mean lower low water about 1.5 km 

east of Halape (fig. 7), where it was channeled 

against a low cliff trending about normal to the 

coast. Generally the tsunami rose highest on the 

low ground within the Halape-Keauhou Landing 

area, where it averaged about 9 m above low water. This part of the coast subsided 3 3.5 m during 

and immediately after the earthquake; it is not 

known whether the wave swept the coast before 

or after the subsidence was complete.

The scouring action of the tsunami was most 

extensive in this region. Coconut palm trees were 

rarely felled by the wave, but most other trees, 

particularly keawe, were totally uprooted, shattered, and carried up to the high splash mark (fig. 

9). One 9-m-high casurina tree (iron-wood) at 

Keauhou Landing remained standing off the 

submerged coast but was badly scarred 3 m above 

sea level by debris carried by the wave. The high 

splash mark is marked on land by a pile of trees,

bagasse, rocks, and other debris and by the inland 

margin of a zone of withered leaves and grass 

killed by salt water.

The tsunami deposited great numbers of small 

fish, crabs, and other sea life up to the high splash 

mark, but rarely were large water-worn beach 

cobbles and coral heads carried this far. The 

stench of rotting marine life was strong for many 

days afterward. Angular blocks of lava picked up 

on land were commonly piled at the high splash 

mark by the tsunami. Blocks about 30 cm in size 

were most numerous in these piles; some were 1 

m in greatest dimension.

The speed at which tsunamis travel is a function of water depth the deeper the water, the 

greater the speed. In deep water (6,000 m or 

more) where there are no islands nearby, a 

tsunami may move as fast as 950 km/hr; whereas 

in shallow water (180 m or less), it may move as 

slowly as 150 km/hr. The average velocity of the 

November 29 tsunami, as determined from timedistance relations (table 3; fig. 10), varies within

FIGURE 9. Part of a keawe tree toppled and scarred by wave action at Keauhou Landing. Note coconut palms standing in

the sea.

14
TABLE 3. Tsunami characteristics as recorded by some Pacific tide gages, supplemented by visual observations

Source1

VO

VO

TG

VO

TG

VO

TG

TG

TG

TG

TG

TG

TG

TG

TG

TG

TG

TG

TG

TG

TG

TG

Site

Hawaii

Punaluu, Hawaii

Honuapo, Hawaii

Hilo, Hawaii

Kailua-Kona, Hawaii

Kahului, Maui

Hana, Maui

Honolulu, Oahu

Moku o Loe, Oahu (Kaneohe)

Nawiliwili, Kauai

California

Bodega Bay

Imperial Beach

Long Beach

Los Angeles

Newport Beach

Port San Luis

San Francisco (Fort Point)

San Diego

Alaska

Sitka

Yakutat

Pacific

Johnston Island

Wake Island

Pago Pago, American Samoa

Approximate 

arrival 

time, G.m.t.2

14:58

15:00

15:08-15:11

15:15

15:28

15:30

15:37

15:39-15:42

15:44-15:48

19:55-20:17

20:30

21:33

21:33

21:05

20:04

20:28

20:44

21:12-21:25

21:47

16:58-17:11

20:18-20:29

20:33

Approximate 

traveltime3 

(hr. min.)

0:10

0:12

0:20-0:23

0:27

0:40

0:42

0:49

0:51-0:54

0:56-1:00

5:07-5:29

5:42

6:45

6:45

6:17

5:16

5:40

5:56

6:24-6:37

6:59

2:10-2:23

5:30-5:41

5:45

First 

motion

Rise?

Rise?

Rise

?

Rise

?

Rise

Rise

Rise

?

Rise

Rise

Rise

Rise

Rise

Rise

Rise

Rise?

Rise

?

?

?

Maximum 

amplitude 

(m)

1.7

.9

.2

<.l

.3

.4

.4

.2

.3

.2

.8

.2

.1

.2

<.l

.1

<.l

.2

Distance4 

(km)

57

65

43

108

280

190

368

371

535

3734

4042

3974

3965

3992

3793

3752

4033

4495

4626

1558

4017

4154

Average 

velocity 

(km/hr)

342

325

130-112

240

489

271

449

436-412

575-573

729-681

709

589

587

636

720

662

680

702-679

663

719-654

730-707

722

JTG, tide gage; VO, visual observation. All tide gages operated by National Oceanic and Atmospheric Administration, U.S. Dept. Commerce. 

2Reported as hours and minutes, Greenwich mean time (G.m.t.); to obtain Hawaiian standard time (H.s.t.), subtract 10 hours. Range of time indicates 

indefinite beginning of wave: no wave measurable before first time given, and definite wave measurable after second time given. 

3Reported as hours and minutes after the start of 7.2-magnitude earthquake (14:48, G.m.t.). 

''All distances are direct great circle routes from earthquake epicenter at lat 19°20' N., long 155°02' W.

the expectable range. Tide-gage data clearly show 

retardation of the wave velocity in shallow water 

or where islands impeded the direct movement of 

the wave front. The tsunami velocity for passage 

between and along the Hawaiian islands was typically about 500 km/hr or slower, but the openocean velocity was about 700 km/hr (fig. 10). The 

wave was delayed about 1 hour at Long Beach 

and Los Angeles, and one-half hour at Newport 

Beach, probably because of retardation related to 

shallow water adjacent to the Channel Islands 

fronting these shore sites.

The islandwide pattern of wave heights for the 

November 1975 tsunami is similar to that for the 

April 1868 tsunami, generated locally by a large 

earthquake off the south coast (fig. 11). In 1868 as 

in 1975, the highest waves affected the island's 

southeast coast from Cape Kumukahi to South 

Point. In contrast, patterns for tsunamis generated by crustal disturbances originating near the 

North and South American continents, as in 

1946, 1957, and 1960, show maximum heights 

along the northeast and west coasts (fig. 11). The 

1946 wave was produced by a tectonic event in 

the Aleutian Islands accompanied by a magnitude 8 earthquake. The 1960 tsunami was generated by a disturbance in Chile accompanied by 

a magnitude 8.2-8.5 earthquake.

Tide gages at all locations where the first arrival of the November 29 tsunami was well defined 

recorded an initial rise of sea level (table 3). This 

would be expected if the south flank of the volcano 

slumped seaward, as indicated by observations 

and geodetic data. The slumping of a large part of 

Kilauea's south flank would produce a decrease in 

the volume of the ocean basin and a local upward 

displacement of the seawater column to produce 

the tsunami. An alternative explanation would 

require an overall rise of the ocean floor, again 

decreasing the volume of the ocean basin.

THE ERUPTION

About half an hour after the main shock, seismographs near the summit of Kilauea began to 

record shallow, high-amplitude harmonic tremor, 

a distinctive type of seismicity associated with 

movement of magma. At 0532 the sky over 

Kilauea glowed yellow-orange as fluid, gas-rich 

lava began to fountain from a N. 85° E.-trending 

fissure about 500-m long on the caldera floor, just

15
 7

 6

 5

 4

 3

©NEWPORT

X

OS AN DIEGO 

jZ. OPAGO PAGO 

SAN FRANCISCO© WAKE^IMPERIAL BEACH

^X^^

LUISX

 I

 0

/ OYAKUTAT 

LOS ANGELESGDLONG BEACH

1000

I

2000 3000 

DISTANCE, KM (all great circle routes)

4000

FIGURE 10. Plot of approximate tsunami arrival times relative to distance from point of generation (data of table 3).

northeast of Halemaumau (A, fig. 12). The new 

lava issued from a continuous line of fountains as 

much as 50 m high. Within 15 minutes, the fountains decreased to 5-10 m high (fig. 13), eventually dying out about 0700. The fountains fed a 

small basaltic pahoehoe flow that spread mainly 

north from the eruptive fissure, eventually covering an area of about 0.25 km2 on the caldera floor 

(fig. 14). As fountaining abated, emission of gases 

became increasingly vigorous. After eruption of 

lava had ceased, jetlike, noisy degassing continued from the vents.

Weak eruptive activity resumed at 0830 with 

copious fuming from a point on the northeast wall 

of Halemaumau, 21m above the crater floor (B, 

fig. 12). The rate of fume emission increased 

rapidly, and within a few minutes lava began to 

erupt in 4-5 m high fountains that fed narrow, 

sluggish rivulets moving slowly down the sides of

a low spatter cone built around the vent. A small 

pool of lava gradually accumulated on the floor of 

Halemaumau at the base of the cone, while jetlike 

emission of gas continued at the vent.

At 0953 another vent (C, fig. 12) opened on 

Halemaumau's northeast wall 18 m above the 

crater floor, 107 m southeast of vent B. The activity at vent B diminished somewhat as lava began 

to spurt to 3-5 m heights at vent C. The proportion of gas to lava emitted by both vents gradually increased, and after 1100 the material 

erupted was mostly incandescent blocks sporadically thrown nearly 100 m high during loud gas 

bursts. The ejecta largely fell back into the vents, 

and by 1330, molten lava was no longer visible 

and the rate of degassing had greatly decreased.

At about 2005 eruption resumed intermittently in Halemaumau from these same two vents, 

producing lava fountains at times 100 m high

16
90 180 270 360

FIGURE 11. Height of tsunamis (in meters above mean lower 

low water) on the island of Hawaii for five major events; 

1868 and 1975 tsunamis were generated locally. Coastal 

points are located by their azimuth from a point in the 

center of the island at lat 19°30'N., long 155°30' W. 

Azimuth of arrival path of waves shown by arrow. Arrival 

path for 1868 tsunami (dashed arrow) not known exactly. 

Data for 1946, 1957, and 1960 tsunamis from Eaton, Richter, and Ault (1961); data for 1868 tsunami from several 

sources, chiefly Wood (1914). See Suggested Reading for 

complete references.

and accompanied by vigorous degassing. By 2200 

the eruption had ended, but noisy degassing 

continued until 0200 on the morning of November 30.

The lava from vents B and C in Halemaumau, 

judged by its high viscosity, probably was erupted 

at a relatively low temperature, perhaps from a 

body of magma trapped in a pocket high within 

the volcano. The total volume of lava produced 

during this short-lived eruption was small, approximately 250,000 m3 from vent A, 3,200 m3 

from vent B, and 300 m3 from vent C (fig. 12).

The eruption was not unexpected, as tiltmeter 

and other geodetic measurements had indicated 

that Kilauea had been inflating steadily since its 

last eruption in December 1974. The amount of 

inflation caused by gradual accumulation of 

magma at shallow depths within the volcano had 

reached a level approaching that of several recent 

eruptions. The November 29 eruptive activity 

was apparently triggered by the 7.2-magnitude 

earthquake. The small volume and brief duration 

of the eruption suggest that the shallow magma 

might not have reached the surface under its 

own buoyant energy without a triggering mechanism apparently provided by the violent ground 

shaking.

GROUND MOVEMENTS

On November 29, the summit and south flank 

areas of Kilauea were severely deformed by vertical and horizontal displacements of several 

meters forming numerous ground cracks and 

faults. At Halape, ground subsided as much as 3.5 

m, and 20 km to the east, the inhabited Kalapana 

area sank nearly a meter. Inland, a nearly 

continuous zone of ground cracking and faulting, 

with vertical offsets as much as 1.5 m, formed for 

about 25 km along the Hilina fault system. 

Smaller scale slumping, sliding, and rock falls occurred widely as a result of ground shaking; such 

movements extensively damaged roads and trails 

in Hawaii Volcanoes National Park. Precise determination of the magnitude and patterns of 

ground displacements will be possible only after 

an extensive geodetic survey now under way.

SUBSIDENCE OF THE SOUTH COAST

At Halape, the subsidence left a grove of 

coconut palms standing in water averaging 1.2 m 

deep and 100-150 m landward of the presubsidence shoreline (fig. 15). Halape's old rocky beach 

is submerged, but a larger, sandy beach had 

formed by mid-December 1975. Broad areas of the 

peninsulas at Kakiwai and Kalue, 2 and 3 km 

respectively west of Halape, are now submerged 

beneath crashing surf. A shallow, tranquil lagoon 

covers 2.2 hectares (1 hectare=2.47 acres) of what 

formerly was a sand-covered flat above a low sea 

cliff at Kaaha, 1.5 km west of Kalue. At Keauhou 

Landing, 2.3 km east of Halape, a brackish 

Hawaiian water well is submerged, the narrow 

beach destroyed, and its fringing thicket of keawe 

trees swept away.

17
FIGURE 12. Sketch map of recent vents and lava flows, Kilauea Caldera and vicinity. Approximate area covered by the 

November 29, 1975, flow shown by hachures; principal fissure (A) by heavy black line. The two minor vents (B and C) 

are at the base of the northeast wall of Halemaumau Crater. (Base map from Halemaumau Trail, 1975, Hawaii Natural 

History Association.)

Few landmarks against which the amount of 

subsidence could be visually estimated occur between Keauhou Landing and Kalapana, nearly 

20 km farther east, but several small black-sand 

beaches formed in 1970-72 near Apua Point are 

now underwater.

At Kalapana, a broad shallow lagoon now occupies an area between Kalapana and Hakuma 

Point that was previously muddy or even dry during low tide. Two segments of the highway between Kalapana and Harry K. Brown Park were 

regularly flooded at high tide after the subsidence; they have since been built up. At the renowned Kaimu black-sand beach, 1 km northeast 

of Kalapana, wave swash now enters the coconut 

grove fringing the beach, eroding the sandy platform in which the palms are rooted.

The amount of subsidence was measured at 

several localities along the coastline from Honuapo to Kaimu shown in figure 16; further data 

will become available in the area northeast of

Kaimu once level lines have been reoccupied. 

Most measurements were made directly from 

postsubsidence sea level to points of previously 

known elevation, including benchmarks, triangulation stations, topographic control points, and 

tide gages. All measurements were adjusted to 

mean sea level using the tide tables to determine 

the absolute subsidence of the land. Estimates of 

precision indicated on the profile (fig. 17) are 

based on the method of determination and the 

quality of the observation.

The maximum measured subsidence, about 

3.5 m, took place in the Halape-Keauhou Landing 

area, about 25 km west of the epicenter of the 

main earthquake. Kalue may have subsided by a 

comparable or even somewhat greater amount, as 

suggested by relations near a previously established tidal reference point that was not found 

and was possibly dislodged by the earthquake. 

The amount of subsidence decreases in both directions from this central area. Toward the south18
FIGURE 13. Lava fountains on floor of Kilauea Caldera at about 0600, November 29, 1975. View from near west end of

eruptive fissure; fountains are about 10 mm high.

west, measurements indicate definite subsidence 

at Na Puu o na Elemakule and Kuee but not in 

the vicinity of Kamehame Hill (figs. 1 and 16). 

Continuously recorded water-level data for a well 

at Punaluu indicated about 0.1 m uplift of land, 

and the Honuapo area showed no detectable 

change with present measurements. Toward the 

east, the amount of subsidence decreases from 

Keauhou Landing to Kaena Point, then remains 

at about 1-2.2 m to Kupapau; releveling of a short 

section along the highway near Kaena Point indicates westward tilting of nearly 10 cm/km. Subsidence was about 75 cm at the Kupapau tide 

gage. The Kalapana area sank a maximum of 

about 85 cm; releveling suggests that about 64 cm 

of this amount results from the regional subsidence and that 21 cm is accounted for by differential dropping or abrupt northward or eastward 

tilting of the previously known Kalapana graben 

(fig. 17). As seen in figure 17, the zone of subsidence is asymmetric, terminating more abruptly 

on the west than on the east side.

The subsidence of the south coast disturbed the 

equilibrium of shoreline processes. Wave erosion 

of cliffs and headlands, particularly during storm 

periods, will be more vigorous because deeper 

water permits higher energy waves to attack 

them. Old beaches will be eroded and redistributed rapidly until a new quasi-equilibrium is established. New beaches may develop, as at 

Halape.

FAULTING IN THE HILINA SYSTEM

Apparently concurrent with the subsidence, a 

nearly continuous zone of ground breakage 

formed along the Hilina fault system, a zone 

characterized by south-facing, normal fault 

scarps as high as 500 m (fig. 18). The new breakage along the Hilina fault system consists of a 

series of steep normal faults, mostly along 

preexisting fault traces, with displacements systematically down to the south. In places, the new 

fault displacement is obscured by extensive 

slumping and landsliding which occurred along 

all of the steep scarps.

19
FIGURE 14. Oblique aerial view to southwest showing floor of Kilauea Caldera, and distribution of lava flow of 

November 29, 1975. Fume rises from the main vent fissure, which cuts across fissure of 1954 eruption. Halemaumau in background.

20
The new faulting extends for about 25 km along 

the trend of the Hilina system and has vertical 

offsets of as much as 1.5 m. In detail, the new 

faults are discontinuous and en echelon in pattern; individual breaks extend a few ten to a few 

hundred meters. Overall, they define a nearly 

continuous zone of normal faulting between more 

coherent blocks, whereas elsewhere on Kilauea, 

the pattern is widespread landsliding and slumping of relatively incoherent material from steep 

slopes.

In the past lava flows have cascaded over most 

of the "palis" (Hawaiian for cliffs or scarps) of the 

Hilina fault system (fig. ISA), gradually building 

them southward toward the sea. The new ground 

rupture took place near the top of the palis, presumably along the buried faults that originally 

created the cliffs. Some palis, such as the seaward 

flank of Puu Kaone (figs. 18B), have not been 

built seaward by draping of younger flows, but 

rather have retreated northward through erosion; 

hence, ground rupture took place near the base of 

these scarps (fig. 19).

Most of the new faulting occurred along the 

northern parts of the Hilina system; several old 

faults near the coast show no new ground rupture. The most continuous zone of breakage and 

the largest vertical offsets are along the northern 

edge of the system 5 to 10 km north and northeast 

of Halape (fig. 16), where vertical displacements 

of 0.5-1.5 m occur for a distance of more than 15 

km. To the south and southwest of this zone of 

maximum faulting, vertical displacements of as 

much as 0.5-1.0 m along other faults are common. 

Accordingly, the cumulative observed fault displacement is at least as much as 2.5 m landward 

of the Halape area and accounts for about 70 percent of the maximum measured coastal subsidence in Kilauea's south coast.

Along the southwestern part of the Hilina fault 

system, new ground breakage is evident along 

several northeast-trending zones over an extent 

of at least 5 km (fig. 16), with vertical displacements locally as much as 1 m. Much of the ground 

movement in this area, however, seems to have 

resulted in only slight readjustment along 

preexisting fractures.

In addition to the main faults, many cracks 

opened within the Hilina system, indicating a 

component of horizontal extension. Most cracks 

are old, but freshly broken rocks and torn vegetation indicate renewed movement on many of

these during the November 29 events. Small new 

cracks in dirt and soft sediment, with opening of 

as much as a few centimeters, are common near 

the larger bedrock cracks, suggesting net extension across the Hilina system.

Geodimeter3 measurements of lines across the 

Hilina fault system indicate that horizontal 

changes of 1 m or more were common; one 5.5- 

km-long measurement line extended 5.8 m, 

another 5.5-km-long line contracted 3.0 m. These 

measurements, though not yet tied to stable reference stations, suggest a significant seaward 

shift of Kilauea's south flank during the 

November 29 events. As part of the overall seaward and downward movement, fault blocks in 

some areas apparently tilted north, as leveling 

surveys near Kaena Point and Kaimu (fig. 1) indicates landward downtilting of about 1 cm/100 m 

and 1.5 mm/100 m, respectively.

POSTEARTHQUAKE ADJUSTMENTS

Following the catastrophic ground movements 

on November 29, a systematic monitoring program was initiated to detect and document continued deformation in the inhabited Kalapana 

area. Geodimeter measurements of selected lines 

across the Hilina fault system indicated cumulative postearthquake extensions of as much as 

8 cm during December 1975. Similarly, precise 

leveling during December indicated postearthquake relative subsidence of 9 mm localized in 

the Kalapana graben. Geodimeter measurements 

January-February 1976 show that all monitor 

lines had nearly stabilized by mid-February. 

Leveling data for the same time period indicate 

continuing subsidence. At this time (February 

1976), available information suggests that 

Kilauea's south flank has largely stabilized, even 

though relative sinking persists in the immediate 

Kaimu area at an average rate of about 1 cm per 

month. How much longer this rate of localized 

relative subsidence will continue is not known. 

The measured changes cannot be related to sea 

level until the entire leveling network of Kilauea 

has been reoccupied and the results referenced to 

tide-gage data.

LANDSLIDES AND GROUND CRACKS

The intense ground shaking of the main 

earthquake produced numerous rockslides and

3Laser-beam electronic instruments for precise measurement of horizontal distances.

21
FIGURE 15. Preearthquake and postearthquake views of coast illustrating subsidence. A, Preearthquake view of Halape 

area from Puu Kapukapu. B, Postearthquake view of Halape from Puu Kapukapu showing the palm grove standing in 

the sea and the offshore island nearly submerged as a result of 3.5 m subsidence; on November 29, 1975, campers were 

swept by the tsunami into the crack behind the palm grove. C, After subsidence, surf surges through the palm grove at

22
Halape. D, Preearthquake aerial view of Keauhou Landing; note shelter and trees. E, Postearthquake aerial view of 

Keauhou Landing; the shelter and nearly all of the keawe trees have been washed away by the tsunami; palm trees 

now stand in the sea. (Photographs: A, Don Reeser, National Park Service; C, E, Boone Morrison;Z), Robin Holcomb, U.S. 

Geological Survey.)

23
o -i-O.I ±.05 

AMOUNT OF UPLIFT IN METERS

o 1.0 ±.30 

AMOUNT OF SUBSIDENCE IN METERS

1.5

FAULT, DOWNTHROW SIDE SHOWN, 

VERTICAL DISPLACEMENT IN METERS

FIGURE 16. Zones of major faulting in the Hilina fault system and amounts of subsidence along the south coastline related

to the main November 29, 1975, earthquake.

_ 

2 <

 -o

+1-

£

UBSIDENCE, 1 ± O

to

fe -a-

£

1 "'"

-4-

3 1 1 3 = £ _ 2

f f I . 3 IS ii

1 ' I I

i o

11

§

s

__ ^,___

: II) | "'("

«

FIGURE 17. Amount of subsidence at points along the coast 

line from Honuapo to Kaimu. Bars indicate estimated error 

limits given in figure 16; dashed horizontal line, zero 

change. Note disruption of profile along west edge of 

Kalapana graben, suggesting dropping or abrupt tilting of 

graben. (See fig. 1 for geographic locations.)

ground cracks, especially in areas of preexisting 

steep slopes such as fault scarps, crater walls, 

and road cuts.

Rockfalls and landslides occurred along every 

major cliff in the Hilina fault system, and new 

open cracks are conspicuous in soil within 50- 

100 m of the tops of the cliffs, suggesting local 

lurching of the ground toward the free cliff face 

during the shaking.

Some of the largest ground cracks and 

rockslides occurred along the rims of Kilauea 

Caldera and the pit craters of the upper east-rift 

zone. These dislocations caused more than 

$675,000 damage to roads, trails, and viewing 

overlooks in Hawaii Volcanoes National Park. 

Visitor overlooks at Keanakokoi, Pauahi, and 

Puhimau Craters slumped downward and outward; parts of them crashed into the craters, and 

gaping cracks as wide as 25 cm formed in the 

parts still left, rendering them too unstable for 

continued use by park visitors (fig. 20).

Cracks as wide as 1 m opened in the Waldron 

Ledge area on the northeast side of Kilauea Caldera, destroying a 1-km segment of the Crater 

Rim Road (fig. 21). Extensive new cracking damaged the Crater Rim Road near Kilauea Military 

Camp and blocked the Chain of Craters and

FIGURE 18, Hilina fault system. A, Postearthquake, lowangle aerial view of Kilauea's south flank looking northeastward. Background shows some lava-draped "palis" 

(cliffs) of the Hilina fault system. Foreground shows the 

coast at Keauhou Landing (note the palm trees in water and 

the dark swath indicating the area washed by the tsunami). 

B, Preearthquake, high-angle aerial view of part of the 

Hilina fault system. Halape area upper right-hand corner; 

Puu Koae is top of cliff at left center.

24
25
FIGURE 19. Vertical offset of about 1.5 m along new fault, south face of Puu Kaone (see fig. 18B).

Hilina Pali Roads (fig. 12). While most of the 

ground breakage was extensional, producing new 

or widened cracks, local compressional features 

formed where slices of ground swayed between 

bounding open fractures and ended on one side or 

the other. A 5-cm partial closing of one crack in 

this manner produced a striking chevron fold 

across a road on the southeast side of Kilauea 

Military Camp (fig. 22). In a few places, movements along cracks produced apparent lateral 

offsets of as much as 10 cm (fig. 23).

Conspicuous cracking occurred along the Koae 

fault system south of Kilauea Caldera. In this 

area characterized by numerous open fissures, 

some old cracks opened, others closed, and in 

many sand-covered areas, small new cracks are 

evident. Limited geodimeter and leveling data 

indicate that horizontal extensions of as much as 

2 m and significant southward tilting occurred 

across the Koae fault system. Much and perhaps 

all of the cracking had formed by a few hours 

after the earthquake.

DEFORMATION RELATED TO MAGMA MOVEMENT

Kilauea's summit area began to deflate as soon 

as the eruption began. The rate of deflation, measured by a tiltmeter in a vault near the Hawaiian 

Volcano Observatory, was 2-3 microradians4 per 

hour during the early part of the eruption, gradually increased to 4-5 microradians per hour later 

in the morning, continued at this high rate for 

about 30 hours, then at lower rates for more than 

a week (fig. 24). Total deflation recorded was 

about 241 microradians, the largest deflation in 

the summit area since the 1960 Kapoho eruption.

Leveling data indicate that the maximum subsidence in the summit area is at least 1.2 m, centered about 2 km south-southeast of Halemaumau (fig. 12). The volume of deflation is computed 

to be at least 68 million m3 , about 270 times 

the volume of lava erupted on November 29 

(0.25+million m3) The large ratio of volume of 

deflation to volume of erupted lava suggests that

"One microradian represents a tilt of 1 mm in 1 km.

26
FIGURE 20. Ground cracking and landslides in Hawaii Volcanoes National Park. A, Back part of viewing overlook 

area at Puhimau Crater slumped completely into the crater, leaving guardrail projecting into space. B, Aerial view 

of large cracks in viewing overlook area of Pauahi Crater. C, Small landslide from spatter and cinder cone partially 

blocking Chain of Craters Road (Photographs: B, Hugh Clark, Honolulu Advertiser; C, Boone Morrison.)

27
FIGURE 21. Large crack in Crater Rim Road, Hawaii Volcanoes National Park. Cracking resulted from slumping of 

rim block toward caldera, the edge of which is a few meters 

to right of road.

the deflation was caused primarily by subsurface 

migration of magma beneath the summit area to 

unknown sites within the rift zones.

CAUSE OF EARTHQUAKE 

AND GROUND MOVEMENTS

Some of the catastrophic events of November 

29, 1975, were caused by ground shaking or subsidence along the south coast. The tsunami was 

generated either by the sudden downward and 

seaward movement of a large segment of the 

south flank of Kilauea, which literally pushed a 

large wave into motion, or by the sudden uplift of 

the sea floor at the base of the volcano's slope, 

where a pronounced bulge (fig. 25) may reflect 

similar events in the past. The brief eruption at 

Kilauea's summit may have been triggered by 

opening of earthquake-induced fractures above 

the swollen magma storage reservoir. Subsidence 

and some ground cracking of the summit area apparently resulted from movement of magma from 

beneath the summit into the rift zones and possibly elsewhere in Kilauea's flanks. Landslides on 

steep slopes and cracking of roads were clearly 

surficial effects caused by ground shaking.

What caused the 7.2-magnitude earthquake

FIGURE 22. Small compressional chevron fold across road on 

southeast side of Kilauea Military Camp, Hawaii Volcanoes 

National Park.

and the massive movements of Kilauea's south 

flank, during which a large slab, several 

thousand square kilometers in extent, apparently 

broke loose along the north edge of the Hilina 

fault system and moved downward and seaward 

several meters? Some scientists argue that the 

earthquake triggered the catastrophic ground 

movements, while others argue that the ground 

movements triggered the earthquake. Definitive 

answers to this fundamental but controversial 

question will require careful study of the seismic 

and geodetic data, much of which is still being 

collected. At this time (February 1976), only a few 

percent of the expected total number of aftershocks have been instrumentally recorded and 

analyzed. Seismic data thus far studied define a 5- 

to 9-km-wide belt of aftershock activity bounded 

on the south by the northernmost faults of the 

Hilina system (fig. 2). Most of the aftershocks 

occur at a depth of 5-7 km. Yet, the zone of major 

ground dislocations is south of this well-defined 

belt of aftershock activity. The reason for the apparent absence of aftershocks in the part of 

Kilauea's south flank most deformed is not known 

at present.

One fact seems clear, however. Regardless of 

which came first, the earthquake or the massive 

ground shifts, the sudden movement of such a 

large block of ground was caused ultimately by 

gravitational stresses on an unstable part of the 

volcano. The surface of Kilauea's south flank

28
FIGURE 23. Collapse offsetting center line of Chain of Craters Road, just south of Pauahi Crater, Hawaii Volcanoes

National Park.

slopes about 8° to a depth of about 4.5 km below 

sea level. The flank is unstable because (1) it is 

almost completely detached from the rest of the 

volcano along fractures of the two rift zones and 

the Koae fault system (fig. 1); (2) it consists in 

part of loose, poorly coherent debris formed earlier in Kilauea's growth; and (3) it is subject to 

seaward shoving by magma injected into the rift 

zones. Piling up of lava flows on the surface of the 

south flank further increases the gravitational 

instability. Eventually, when some critical 

threshold is exceeded, part of the flank tears loose 

along the Hilina fault zone, and a mammoth 

block of ground lurches downslope (seaward). In a 

sense, the Hilina fault system marks the heads of 

giant landslides (fig. 25).

The sudden ground movements on November 

29 were doubtless similar to those that have

formed the Hilina fault system, and the event is 

almost certainly the latest in a series of many 

similar episodes that have built the palis to their 

present heights. As long as Kilauea remains active, gravitational and magma-induced stresses 

will inexorably build up, and the mobile south 

flank will shift seaward and downward episodically and abruptly, providing stress relief. Then 

the cycle will begin anew. Consequently, if 

Kilauea's prodigious eruptive activity persists, 

such events as occurred on November 29 will recur, perhaps at a tempo suggested by the earthquakes and associated subsidence of 1823(7), 

1868, and 1975.

COMPARISON WITH 1868 EVENTS

The events of November 29, 1975, and April 2, 

1868, are comparable in many respects, although

29
AUG' 

1975

FIGURE 24. Changes in tilt May-December 1975, as recorded 

on E-W component of water-tube tiltmeter located in vault 

near Hawaiian Volcano Observatory. Plot shows E-W component of deflation associated with November 29 events to 

be about 145 microradians. N-S component of deflation (not 

shown), approximately 193 microradians, resulted in total 

deflation of about 241 microradians.

the 1868 earthquake was apparently stronger, estimated to be between magnitude 7.5 and 8.0 

from damage effects (intensity). During both 

episodes, the south coast of Kilauea subsided, a 

tsunami occurred, Kilauea erupted a small volume of lava, and the summit area of the volcano 

collapsed. A brief summary of the 1868 events is 

given below: 

March 27, 1868

(a) Numerous small earthquakes were felt; the 

swarm continued until April 2.

(b) A small eruption occurred on the summit of 

Mauna Loa.

(c) Eruption in Kilauea Caldera, characterized by active lava lakes continued. 

April 2, 1868

(a) At 1600, a very large earthquake occurred 

that caused great damage and was felt as 

far away as Kauai, 500 km to the northwest. Stone buildings were destroyed or 

damaged throughout the south half of 

Hawaii, especially in the Ka'u District. 

Large ground cracks opened on the south 

and southwest flanks of Kilauea.

(b) A mudflow triggered by the earthquake 

swept across Wood Valley, Ka'u District, 

killing 31 people. Landslides and rockfalls 

were dislodged from steep cliffs throughout the island, killing two people near 

Hilo.

(c) The southeastern coast of Kilauea subsided 

as much as 2.1 m.

(d) A tsunami destroyed all coastal villages on 

the southeastern side of the island, killing 46 people. The tsunami reached 18 m 

above sea level (fig. 7).

(e) A small eruption occurred on the side of 

Kilauea Iki Crater, while lava lakes in 

Kilauea Caldera continued activity. 

Much of the floor of the caldera subsided 

nearly 100 m. A small volume of lava was 

extruded on the southwest rift zone of 

Kilauea, 15 km southwest of the caldera.

LESSONS FOR THE FUTURE

In the 20th century, 21 earthquakes greater 

than 5.5 in Richter magnitude have occurred in 

Hawaii (1918, 1919, 1929 (3), 1933, 1938, 1940, 

1941, 1943, 1944, 1950, 1951, (2), 1952, 1954 (2), 

1955, 1962, 1973, 1975). Earthquakes of this 

magnitude were probably fairly frequent in past 

centuries, before the days of quantitative seismic 

recordings. Large earthquakes in Hawaii have 

caused millions of dollars in damage, but relatively few injuries and deaths. Tsunamis have 

been the most disastrous natural hazards on 

Hawaii, causing considerable bodily injury and 

less of life as well as property damage; since the 

beginning of the 19th century, more than 350 

people have been killed by tsunamis.

The Pacific Tsunami Warning System, which 

covers the Hawaiian Islands, is geared to alert 

residents of the impending arrival of tsunamis 

generated on distant shores around the Pacific. 

Waves produced by tectonic movements in Alaska 

and Chile require about 5 to 15 hours respectively 

to reach Hawaii, ample time to activate the Civil 

Defense warning system. However, the time between a locally generated earthquake and the resulting tsunami is generally too short for such a 

warning. The November 29, 1975, wave arrived 

at Hilo only 20 minutes after the earthquake. The 

tsunami warning siren first sounded in Kona approximately 30 minutes after arrival of the first 

wave.

The only practical warning system for such 

local events is an educated and informed 

populace. The basic warning of a possible tsunami 

is the earthquake itself. If ground shaking makes 

standing difficult, produces significant rockfalls, 

and damages structures, one should immediately

30
FIGURE 25. Oblique map of the south half of the island of Hawaii as viewed from the east showing submarine topography. Heavy lines define new faulting, and dotted lines indicate amount of coastal subsidence in meters during 

the 1975 earthquake. Physiographic drawing by Tau Rho Alpha.

31
move to high ground. Experience from the 1975 

tsunami suggests the following:

(1) In historic times, tsunamis affecting 

Hawaiian coastal areas have attained maximum 

heights of nearly 17 m locally; however, past 

tsunami heights have rarely exceeded 12 m above 

sea level. Obviously, any inhabited coastal areas 

below 12 m are particularly subject to possible 

tsunami damage. Beach campers are especially 

vulnerable to tsunamis, because they are close to 

the sea and often in remote areas not covered by 

warning or communications systems. In such remote beach areas, it would be advisable to locate 

overnight shelters 12m above sea level, if at all 

possible. As only large earthquakes are preceded 

by foreshocks, campers should be instructed to 

move to high ground if they experience any felt 

earthquake. Not all large earthquakes produce 

tsunamis, but it is more prudent to have a few 

false alarms than tragedies.

(2) A reliable warning system for locally generated tsunamis should be established, utilizing 

strong-motion seismic instruments (accelerometers). Such a system would provide at most only 

25 minutes of advance warning for Hawaii Island 

residents, but even a few extra minutes might 

save lives. Such a system would potentially be 

more important for population centers, such as 

Honolulu, on the other islands in the state; which 

probably would have a longer warning. Since 

1868, 12 of the 13 local earthquakes of intensity 

VII or greater that might generate a tsunami 

have been centered around the Big Island; the 

other occurred near Maui. Thus, Honolulu might 

expect 45-55 minutes of advance warning of a 

tsunami generated near Hawaii Island.

At this time (February 1976), Hawaii Civil 

Defense officials have announced a plan to develop a warning system using strong-motion instruments.

(3) According to established Civil Defense procedures, waterfront hotels should move guests 

immediately to upper floors rather than risk 

evacuation across wide areas of low ground.

(4) Residents should be reminded periodically 

of the procedures to take in the event of a locally 

generated tsunami. Such reminders need to be 

given at fairly frequent intervals, because many 

years may pass before any of the Hawaiian islands is again hit by a locally generated tsunami.

(5) The generally unstable nature of Kilauea's

south flank should be considered in any land-use 

decisions for that area.

ACKNOWLEDGMENTS

Gathering of data and preparation of this report were facilitated by the efforts of many individuals and governmental agencies. George 

Pararas-Carayannis, Director, International 

Tsunami Information Center, and Harold Loomis, 

Joint Tsunami Research Effort (NOAA), provided 

tide-gage and other information concerning the 

tsunami that filled in some gaps in our observations. Wayne Hall and Dorothy Radbruch-Hall, 

U.S. Geological Survey, furnished observations of 

tsunami and ground-movement effects. Patrice de 

St. Ours, guest investigator at the Observatory 

from the University of Orsay (France), made important observations of the Kilauea summit eruption. Robert Crosson, University of Washington, 

assisted in the seismic studies.

We greatly appreciate the aid and cooperation 

of various agencies of the County of Hawaii, in 

particular the Civil Defense Agency and Fire and 

Police Departments, and the assistance of the 

officials of Hawaii Volcanoes National Park. 

Kenneth Ellard and Ronald Thrash, helicopter 

pilots for Hawaii County, skillfully provided a 

critical service. The Federal Disaster Assistance 

Administration (Region IX) provided some logistic support for the postearthquake monitoring of 

the Kalapana area. We thank the Halape campers, and many other residents of Hawaii County, 

especially Herbert and Doris Mann of Volcano, 

for useful first-hand descriptions of earthquake 

and tsunami effects, and our colleagues of the 

Hawaiian Volcano Observatory for their long 

hours of work during the hectic time following the 

catastrophic event of November 29, 1975.

SUGGESTED READING

Eaton, J. P., Richter, D. H., and Ault, W. U., 1961, The 

tsunami of May 23, 1960, on the island of Hawaii: Seismol. Soc. America Bull., v. 51, p. 135-157. (An account of 

the 1960 tsunami, including a summary of previous destructive tsunamis that have affected Hawaii.)

Macdonald, G. A., and Abbott, A. T., 1970, Volcanoes in the 

Sea Geology of Hawaii: Honolulu, Univ. Hawaii Press, 

441 p. (Chapter 16 gives an excellent account of Hawaiian 

earthquakes and tsunamis. Chapter 2 summarizes typical 

Hawaiian volcanic activity.)

32
Peterson, D. W., and Mullineaux, D. R., 1976, Natural hazards 

of Hawaii, U.S. Geol. Survey Circular, in press. (A nontechnical summary, in question-and-answer format, of 

the volcanic, seismic, and related natural hazards on the 

island of Hawaii.)

Swanson, D. A., Duffield, W. A., and Fiske, R. S., 1976, Displacement of the south flank of Kilauea Volcano: The result of forceful intrusion of magma into the rift zones: U.S. 

Geol. Survey Prof. Paper 963, 39 p. (A comprehensive 

summary and analysis of geodetic and geologic data 

documenting the seaward movements of Kilauea's south 

flank. On the basis of geodetic observations, this technical 

publication suggested that catastrophic events like those 

of 1868 might be expected in the "not too distant future.")

Wood, H. O., 1914, On the earthquakes of 1868 in Hawaii: 

Bull. Seismol. Soc. America, v. 4, no. 4, p. 169-203. (The 

largest earthquake in Hawaii's history struck in 1868. 

The events of November 29, 1975, were in many ways 

similar to, but less destructive than, the events of 1868.)

33