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EARTHQUAKE AND TSUNAMI OF 22 MAY 1960 IN CHILE

EARTHQUAKE AND TSUNAMI OF 22 MAY 1960 IN CHILE
George Pararas-Carayannis

(Excerpts from archives compiled in preparation of a Catalog of Tsunamis in the Pacific Ocean and for the Catalog of Tsunamis in the Hawaiian Islands. World Data Center A- Tsunami U.S. Dept. of Commerce Environmental Science Service Administration Coast and Geodetic Survey, May 1969)

SUMMARY

The largest earthquake ( Moment magnitude Mw= 9.5) of the 20th century occurred on May 22, 1960, off the coast of South Central Chile. It generated one of the most destructive Pacific-wide tsunamis. Near the generating area, both the earthquake and the tsunami were extremely destructive, particularly in the coastal area extending from Concepcion to the south end of Isla Chiloe. The most extensive tsunami damage occurred at Isla Chiloe, the coastal area closest to the epicenter.

Huge tsunami waves measuring as high as 25 meters, arrived within 10 to 15 minutes after the earthquake, killing at least two hundred people, sinking all the boats, and inundating half a kilometer inland. There were extensive damage and loss of life at Concepcion, Chile’s top industrial city. Near the city of Valdivia, the earthquake and subsequent aftershocks generated landslides which killed 18 people.

At the port city of Valparaiso, a city of 200,000, numerous buildings collapsed. A total of 130,000 houses were destroyed – one in every three in the earthquake zone and approximately 2,000,000 people were left homeless. Total damage losses, including to agriculture and to industry, were estimated to be over a half billion dollars (1960 dollars). The total number of fatalities associated with both the tsunami and the earthquake was never established accurately for the region. Estimates of fatalities ranged between 490 to 5,700 with no distinction as to how many deaths were caused by the earthquake and how many were caused by the tsunami. However, it is believed that most of the deaths in Chile were caused by the tsunami.

The tsunami was also very destructive throughout the Pacific Ocean, but particularly in the Hawaiian Islands and in Japan where there was a tremendous loss of life and damage to property. It took about 15 hours for the tsunami to travel to the Hawaiian Islands – a total distance of more than 10,000 kilometers from the generating area in Southern Chile. The tsunami caused little damage in most of the Hawaiian islands, but the island of Hawaii and particularly the Hilo Bay area were hit the hardest. Destructive waves destroyed completely the waterfront and killed 61 people. Total damage was estimated at $24 million (1960 dollars).

Elsewhere along the western coast of the United States, notable tsunami waves and run-up were begun 15.5 hours after the occurrence of the earthquake in Chile. At Crescent City, California, waves of up to 1.7 meters were observed and minor damage was reported.

Introduction

On May 22, 1960, the largest recorded earthquake this century occurred off the coast of South Central Chile along the Peru-Chile Trench. The earthquake generated one of the most destructive tsunamis in the Pacific. Both the earthquake and the tsunami were extremely destructive in Chile, particularly in the coastal area extending from Concepcion to the south end of Isla Chiloe. The destructive effects of the tsunami were experienced throughout the Pacific Ocean and were particularly devastating in Chile, Hawaii, and Japan.


The May 22, 1960 Earthquake

There was a series of earthquakes. The first occurred on May 21, 1960, at 10h 02m 50s. It caused many casualties and extensive damage at Concepcion and surrounding areas. The May 22, 1960 earthquake occurred at 19:11 GMT, off the coast of South Central Chile, also near the city of Conception, in the Province of Valdivia.

Surface-wave magnitude: 8.6. However, the Moment Magnitude (a better measure of the earthquake’s energy release )was re-estimated at 9.5.

Epicenter: Main event 39.5W, 74.5W

Focal depth: 33 km (20.5 miles). 1960 May 22, 19:11,

A series of earthquakes: Beginning 21 May 1960, there was a series of earthquakes in southern Chile extending over a 1,300 km long zone, between 37and 48 degrees south latitude.

Earthquake Effects in Chile

A number of large foreshocks proceeded the main earthquake by about 30 minutes. The large foreshocks served as a warning and some lives were saved as many people had evacuated buildings and had taken to the safety of open space.

The series of earthquakes and tsunami waves caused many casualties and extensive property damage along the coast of central Chile from latitudes 36 deg South to about 44 deg South. The earthquake was particularly destructive along the coastal area extending from Concepcion to the south end of Isla Chiloe. There was an extensive loss of life at Concepcion, Chile’s top industrial city. Valdivia suffered great damage as well as Puerto Montt. Many small towns and villages were also heavily damaged. Massive landslides, violent volcanic eruptions and extensive dislocations of the land surface were reported in early press reports from Chile.

Estimates of Fatalities and Property Damage: The earthquake and subsequent aftershocks generated landslides which killed many people. The number of fatalities associated with both the tsunami and the earthquake was never established accurately for the region. Estimates of fatalities ranged between 490 to 5,700 with no distinction as to how many of the deaths were caused by the earthquake and how many were caused by tsunami waves. However, it is believed that most of the deaths were caused by the tsunami, while most of the property damage may have been caused by the earthquake. At the port city of Valparaiso, a city of 200,000, numerous buildings collapsed.

Reportedly there were 3,000 people injured, and 717 missing in Chile. The official Chilean government estimate was that 2,000,000 people were left homeless. A total of 130,000 houses were destroyed – one in every three in the earthquake zone. Total damage losses, including to agriculture and industry, were estimated to be over a half billion dollars (1960 dollars).

Collateral Effects – In addition to the tsunami, there were other geologic phenomena associated with this earthquake. There were reports of extensive subsidence, alteration of the shoreline and of local flooding. Regional tectonic subsidence ranged from five to seven feet. There were reports of large landslides. Rock falls and landslides in the Andes formed a lake on the Rio San Pedro, the outlet of Lake Rinihue. On May 24, 1960, forty-seven hours after the main quake, there was an eruption of the Puyehue volcano.

The eruption of Puyehue volcano after the 1960 earthquake.

Source Mechanism of the May 22, 1960 Earthquake

This southern/central region of Chile where the May 22, 1960 earthquake occured is along the great subduction zone between the Nazca oceanic plate and the South American continental plate. Specifically, the earthquake’s focal mechanism was of the thrust-type and was caused by the downward movement of the subducting oceanic plate below the South American plate. This coincided with the Chile triple junction region where elastic strain had accumulated. Continuous crustal deformation associated with oblique convergence and ridge collision in the region had led to substantial deformation and strain accumulation which culminated in this particular May 22, 1960 earthquake. The record of the strain seismogram at the Pasadena Seismological Laboratory showed an unusually long-period (300-600 sec) wave arriving at the P time of a large foreshock which occurred about 15 minutes before the main shock. Based on this observation, a large slow deformation in the epicentral area prior to the major failure, was inferred (Kanamori & Cipar, 1974). The sequence of events is given in the caption of the illustration below.

Earthquake Magnitude: The Great Chilean earthquake of May 22, 1960, was the largest seismic event ever recorded instrumentally in the world. The earthquake’s moment magnitude (MW) was a staggering 9.5. Based on recordings at the Seismological Laboratory in Pasadena, California, the seismic moment for the main shock was determined to be 2.7 . 1030 dyn . cm (Kanamori & Cipar, 1974). The energy released was about one fourth of the total global seismic moment release between the years 1904-1986.

Foreshoks, the Main Earthquake and Major Aftershocks: There were several large foreshocks in the general area which proceeded the main earthquake of 19:11 GMT, on May 22, 1960. The aftershocks continued for weeks. The epicenters of these aftershocks extended from Latitude 37 degrees South to as much as 48 degrees South and from Longitude 71.5 degrees West to 77.0 West.

Proposed focal process of the Chilean earthquake of 1960 (Kanamori & Cipar. 1074) – a) An initial aseismic slip occurred along the lithosphere-asthenosphere boundary at depth; b) small foreshock triggered by the stress concentration caused by the aseismic slip; c) Subsequent resulting rupture at the upper lithosphere-lithosphere boundary resulting in the destructive May 22, 1960 earthquake. The insert shows the vertical cross-section of seismicity in this area given by Stauder (1973).

Fault Length: The extensive distribution of the aftershocks indicates a rather extensive fault zone which was almost 1,000 km long 300 km wide. The estimated fault area was 1.6. 105 km2, and the average dislocation was estimated at 24 m (Kanamori & Cipar. 1974).

Earthquake Intensities: Maximum experienced intensity on the Mercalli Modified scale of the earthquake was XI. Based on the damage the following intensities were assigned to Southern Chile towns: Lebu ( X), Valdivia ( X), Talcahuano (IX), Coronel (i IX), Lota (intensity IX) and. The shocks of 22 May affected especially southern Chile:, Puerto Montt (lower town) (X-XI), Rio Negro ( IX-X), Temuco ( VIII), Osorno ( VII-VIII), Puerto Saavedra ( VII-VIII), Llanquihue ( VII-VIII), Villarica ( VII) (Duke and Leeds, 1963; Rothe, 1961).

Death Toll and Damages: Overall, more than 5,700 killed, 3,000 injured, 2,000,000 homeless, and $800 million damage in southern Chile; tsunami caused 61 deaths, $75 million damage in Hawaii; 138 deaths and $50 million damage in Japan; 32 dead and missing in the Phillippines; and $500,000 damage to the west coast of the United States (Carroll Talley, Jr. and Cloud, 1960, Iida et al. 1967).

Future Large Earthquakes in Southern Chile: This area of Southern Chile where the May 22, 1960 earthquake occurred, is a region where a large earthquake can be expected to occur again. In the last four decades, since 1960, crustal deformation from continuous plate convergence and subduction is building strain which presently is accumulated and accommodated, elastically. When the threshold limits of crustal elasticity are exceeded another major or great earthquake can be expected as well as a destructive tsunami. The recurrence frequency of large earthquakes is estimated to be about 50 years, while smaller and less destructive earthquakes could occur more frequently.

Vertical cross-section of seismicity in the region where the May 22, 1960, occurred (Modified graphics after Stauder, 1973). Note the shallow angle of subduction in the region and subsequent change in the angle of dip of the oceanic plate below the continent of South America.

The Great Pacific-Wide Tsunami of 22 May 1960

The Chilean earthquake of May 22, 1960, generated a large Pacific-wide tsunami which raced across the ocean causing extensive destruction along its path, in other areas along the South American coast but particularly adversely impacting Hawaii, Japan, and other Pacific areas. This tsunami was one of the most destructive events and its impact affected the entire Pacific Basin. The tsunami waves varied in height from 13 meters at Pitcairn Island to up to 12 meters in Hilo, Hawaii, to 7 meters on Japan’s coasts some 17,000 km away. High waves also occurred in other parts of the Pacific.

Tsunami Effects along Peru – Chile Coast

Coastal area on Isla Chiloe, Chile, showing tsunami damage. From Archives of ITIC; Source Unknown)

The tsunami waves began reaching the immediate coastline areas of Chile within 10 to 15 minutes after the earthquake.

Initial reports from Lebu indicated that waves of three to four meters in height were being observed which were causing serious damage to the harbor. A little later there were reports of successive destructive waves arriving at coastal areas of Valdivia, Puerto Montt, Ancud, Caleta Mansa, Corral, y Puerto Saavedra among other places.

Travel Time Chart of the 1960 tsunami across the Pacific Ocean (contour intervals of 1 hour travel time – i.e 22 hours to Japan).

Locally, in Chile, the tsunami affected more seriously an area extending from Concepcion to the south end of Isla Chiloe. At the coastal area closest to the epicenter, huge tsunami waves measuring as high as 25 meters (up to 82 feet), arrived within 10 to 15 minutes after the earthquake, killing at least two hundred people, sinking all the boats, and inundating half a kilometer inland. Death estimates from the tsunami for the entire Peru-Chile coastline ranged from 330 to 2,000 persons.

Aerial Photo of tsunami inundation at Chiloe Island.

The most extensive tsunami damage in Chile was reported from Isla Chiloe. Two hundred deaths were reported here from the tsunami. The inhabitants, fearing the earthquake, took to small boats to escape the shaking. The trough of the tsunami arrived just 10 to 15 minutes after the earthquake, along more than 500 m of the coast. Upon the return of the sea in a thunderous breaker, all boats were lost.

The Effects of the May 22, 1960, Tsunami in the Hawaiian Islands

The great Pacific-wide tsunami traveled a total distance of more than 6,000 miles (10,000 kilometers) from the generating area in Southern Chile before reaching the Hawaiian Islands. Travel time was about 15 hours after the earthquake. The local date in Hawaii was 23 May 1960. The tsunami caused little damage in most of the Hawaiian islands, but the island of Hawaii – and particularly the Hilo Bay area – were hit the hardest. 61 people lost their lives and 282 were injured. Damage costs were estimated at $24 million (1960 dollars)(Iida et al. 1967; Pararas-Carayannis, 1968).

Hawaiian Islands

Hilo: The island of Hawaii was the first of the Hawaiian islands to experience the effects of the tsunami. At about at 12 to 20 minute time intervals, a total of eight tsunami waves arrived. The first of the series arrived at Hilo Bay at about 12:15 on May 23, 14.8 hours after the earthquake. The first wave appeared as a sudden rapid tidal oscillation but did not cause any alarm. Subsequently, the arrival of the second wave was proceeded by a quick recession of the water but again there was not much inundation. The third wave was extremely destructive. It arrived a little after 1 a.m. as a 20 ft. bore and crashed as a massive wall of water, completely inundating about 550 acres of Hilo’s waterfront area and penetrating inland by as much as 3,600 feet. The destruction of this wave caused was unprecedented. It obliterated the entire downtown area of Hilo. Hardest hit was the Waiakea area of Hilo, which had sustained minimal damage previously from the 1946 tsunami – perhaps because of that tsunami’s different direction of approach. Many of the deaths occurred in the Waiakea Peninsula.

Maximum tsunami runup at Hilo Bay was 10.7 meters (about 35 feet) above sea level. Elsewhere, the runup ranged from 3-17 feet (Pararas-Carayannis, 1968). The waves advanced far inland and destroyed much of Hilo’s downtown area as far inland as Kilauea Avenue/Keawe Street and Kekuanaoa Street near Kilauea Avenue. Frame buildings were crushed or carried inland or out to sea. Debris-carrying tsunami waves bent parking meters around telephone polls. A large number of automobiles were destroyed and a 10-metric ton tractor in a downtown showroom was swept away. Boulders of as much as 20 ton in weight were plucked from a seawall and were carried as much as 180 m inland. Only a few buildings constructed with reinforced concrete or structural steel remained standing, but even these sustained considerable damage.

Damage elsewhere on the Island of Hawaii occurred mainly on the west and southern coasts. About a dozen buildings were floated off their foundations, crushed, or flooded. At Napoopoo, six houses were destroyed.T otal damage on the Kona coast was about half a million (1960)dollars.
On the Island of Maui, the damage occurred in the Kahului area. A warehouse and half a dozen houses were destroyed and other warehouses, stores offices, and homes, and their contents were badly damaged. A church floated 6.1 m away from its foundation. There was considerable damage to buildings at Paukukalo, just west of Kahului harbor. There was considerable damage to houses at Spreckelsville and Paia, east of Kahului.

On the Island of Lanai  the tsunami destroyed a beachhouse. On the Iasland of Maui, there was damage to houses in Kihei on the south coast and in Lahaina on the west coast. On the island of Molokai there was some damage to homes, fish ponds, and roads. On the islands of Oahu and Kauai there was only minor damage. On the eastern Honolulu suburb of Kuliouou, there was damage due to flooding to about 50 homes, estimated at $250,000 (1960 dollars). Elsewhere on Oahu there was flooding but no seriouw damage occurred. On the southern coast of the island of Kauai, there was a report of damage a frame building that floated off its foundations (Pararas-Carayannis, 1968; Lander and Lockridge, 1989).

(Honolulu Advertiser photo of tsunami devastation in the downtown area of Hilo, Hawaii)

 

 

 

 

 

Parking meters along the Hilo Bay front were bent from the tremendous force of the tsunami waves. ITIC Archives – U.S. Army Corps of Engineers Photo).

(Honolulu Advertiser photo of tsunami devastation in the downtown area of Hilo, Hawaii)

Photos of Downtown Hilo

The Effects of the May 22, 1960 Tsunami along the coasts of California, Oregon, Washington, British Columbia, Alaska, Japan, Kamchatka, New Zealand and Australia

There were miscellaneous reports of tsunami damage from California, Oregon, Washington, British Columbia and Alaska.

TSUNAMI EFFECTS ALONG THE WEST US COASTLINE AND ALASKA

There were reports of damage in California. At Port Hueneme, the wave was 1.5 meters and caused some damage to the harbor’s infrastructure. At Pacifica it was 1.2 m. high. At Santa Barbara, the tsunami was 1.4 meters and caused damage to boats. At Santa Monica the tsunami height was more than 1.4 m. At Pismo Beach, the tsunami was 2.4 meters but no damage was reported. At Princeton a maximum tsunami height was 2.2 meters and caused damage to two trawlers and other smaller boats.

San Diego: The wave at San Diego was 0.7m and caused considerable damage to the docks throughout the harbor – but paricularly near Point Loma, due to strong currents estimated to be as much as 20-25 knots. The currents swept 12 and 30 m floats from the San Diego Harbor Masters Pier on Shelter Island and swept away two sections of dockage at the Southwest Yacht Club at Point Loma. A 100 ton dredge rammed the concrete pilings supporting the Mission Bay bridge tearing out a 21 m section. More than 80 m of dock were destroyed. A 45 m bait barge smashed eight slips at the Seaforth Landing before breaking in half and sinking. Ferry service was interruped after a ferry crushed into the dock at Coronado knocking out eight pilings. Another ferry was forced 1.5 km off its couse and into a flotilla of anchored Navy destroyers.

Los Angeles and Long Beach Harbor: At Los Angeles the tsunami was 0.9m and caused one death and major damage to small boats.The damage was estimated at $1M (1960 dollars).Major damage in the Los Angeles and Long Beach harbors. In the harbor strong currents of up to 22 km/hr snapped and washed out pilings. Thousands of gallons of gasoline and oil spilled from overturned boats. Several buoys and navigational aids were swept away at Terminal Island. The Coast Guard landing including a tide gage were washed 5.6 km to sea but subsequently recovered. Strong curents in the yacht harbors set 300 small craft adrift. About about 30 boats sunk including a 24 m yacht which smashed into bridge piers causing partial damage to the bridge. About 235 boat slips were lost at the Yacht Center, 110 more were destroyed at the Colonial Yacht Anchorage and at the Cerritos Yacht Anchorage. Total loss to boat facilities were estimated to be about $300,000. At Cabrillo Beach a skin diver was missing and presumed dead.

Santa Barbara: Strong currents set an oil exploration barge drifting and crushing into a dredge, causing an estimated damage of about $10,000. There was additional damage to about 40 small boats that were also set adrift (Lander and Lockridge, 1989).

Santa Monica: There was tsunami inundation of more than 91 m up the beach. A parking lot, just off the Pacific coast Highway, was flooded. There was a drop in the level of the water and the bottom of the breakwater was nearly exposed. Strong currents snapped eight small boats from their mooring lines.

San Fransisco Bay: In San Francisco Bay the wave was 0.4 m at Fort Point. There was some boat damage at San Rafael and the ferry service was interrupted. There was much damage to the dock at Noyo Harbor.

Crescent City: Crescent City experienced notable tsunami waves and run-up. The first wave arrived 15.5 hours after the main earthquake in Chile. Maximum waves of up to 1.7 meters (appr. 5.6 feet) were measured by the tide gauge in the harbo,r but the actual maximum tsunami runup was actually 3.7 meters (Iida et al., 1967) The waves flooded the streets and caused damage to the docks. Two vessels worth $30,000 were lost.

OREGON AND WASHINGTON STATES: In Oregon the tsunami caused damage to boats and mooring facilities and docks at Seaside and at Gold Beach. At Seaside the tsunami height was 1.5 meters.

ALASKA: In Alaska, there was report if a 2.3 meter tsunami and of minor damage to pillings at MacLeod Harbor, on Montague Island and of some minor damage at Cape Pole by a wave of about 1 meter in height. The tsunami was recorded at Massacre Bay (more than 1.7 m), at Sweeper Cove (1.1 m) ,at Seward (0.7 m), Women’s Bay (0.7 m), at Yakutat (0.8 m), at Dutch Harbor (0.7 m), at Sitka ().5 m), and at Skagway (0.2 m) (Cox and Pararas-Carayannis, 1968; Pararas-Carayannis, 1968a, b). The wave was observed at Kake, Juneau, and Ketchikan.

JAPAN: In Japan, the tsunami runups reached more than 6 m. There was extensive destruction along the coast of Honshu. 199 people lost their lives, 85 were missing, and 855 more were injured. A total of 1,678 homes were destroyed (Iida et al. 1967). Damage was estimated at $50 million (1960 dollars).

NEW ZEALAND, AUSTRALIA, KAMTCHATKA AND OTHER PACIFIC AREAS

New Zealand, Australia, Kamchatka and many other locations in the Pacific Basin were impacted by this tsunami.

REFERENCES

Bulletin of Seismological Society of America (BSSA). “Seismological Notes”.

Carroll Talley, Jr. H and William K. Cloud, 1960; United States Earthquakes 1960, U.S. Department of Commerce, Coast and Geodectic Survey Report.

Cox, D.C. and Pararas-Carayannis, G. 1968. A Catalog of Tsunamis in Alaska. Data Report Hawaii Inst.Geophys. Mar. 1968.

Iida, K., D.C. Cox, and Pararas–Carayannis, G., 1967. Preliminary Catalog of Tsunamis Occurring in the Pacific Ocean. Data Report No. 5. Honolulu: Hawaii Inst.Geophysics, Aug. 1967.

Kanamori, H. & J.J. Cipar, 1974. Focal Process of the Great Chilean Earthquake of May 22, 1960. Physics of the Earth and Planetary Interiors, 9 (1974) 128~136, North-Holland Publishing Company, Amsterdam

Lander, J. F. and Lockridge, P. A., 1989, United States Tsunamis (including United States possessions) 1690-1988: U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, 265 p..

Pararas-Carayannis, G., 1968a, Catalog of Tsunamis in the Hawaiian Islands. Hawaii Inst.Geophysics Report. Jan. 1968.

Pararas-Carayannis, G., 1968b. Tsunami Height Report, World Data Center A-Tsunami Report 1968…

Stauder, W., 1973. J. Geophys. Res., 78: 5033-5061

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