Some Notable Earthquakes
Alaska, 1964
Lisbon, Portugal, 1755
Izmit, Turkey, 1999
The 1964 Alaskan Earthquake
Introduction
• One of the most famous earthquakes to hit North America
• One of the largest to strike North America
• Exceptionally well studied
Basic Data
• Date and Time
– March 27, 1964—Good Friday
– 5:36 p.m. local time
• Magnitude
– 8.4 (USGS)
– 8.3-8.6 reported
• Depth of focus—30 km (~20 miles)
• Epicenter near the head of Prince William Sound
More Data
• Felt Area—300,000 mi (800,000 km2)
• Area of damage—30,000 mi2 (80,000 km2)
• Ground was displaced over an area of 77,000 mi2 (200,000
km2)
• The rupture extended 800 km (480 miles) parallel to the
Aleutian Trench
• Maximum uplift of 10 meters on land, 15 meters on the sea
floor, but this may be exaggerated due to soft sediment
deformation
• Subsidence exceeded 2 meters
2
More Data
• Dominant horizontal motion of the land was the the
southeast.
• Deaths
– 131 total
– 122 associated with tsunami
• 16 of these were in California and Oregon
• 71 blamed on local, slump-generated tsunami
– 9 from effects of shaking
– Low because of low population density and timing
Still More Data
• Property Damage
– $300 to $500 million (1964)
– Extensive damage to tall structures
– Well-built frame structures performed well
• Waves had too long a wavelength to damage small structures
• Dominant horizontal motion of the land was to the
southeast
Effects
• Tsunami
– Seismic sea wave (tidal wave)
– Chenga Island
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Peaceful island home for about 80 people
Wave arrived before the ground even stopped shaking
Swept 100 feet up the hillside carrying away people, the church, and every single home
Only the schoolhouse and the cemetery remained
23 of the 80 inhabitants were killed
– Struck the Kenai Peninsula within 19 minutes
– Kodiak Island within 34 minutes
– Devastated coastal areas in Valdez and Seward
Tsunami Information
– Total tsunami damage in Alaska was $84 million
– Waves were 22 feet high at Crescent City, CA
– Waves hit Hawaii and Japan, but damage was minor due to
dirctional aspects
• Japan was hit 7 hours after the quake
• Kwajalein in 10 hours
• Peru in 15.5 hours
Crescent City Tragedy
• 1600 miles from Chenega Island
• People in low-lying areas were warned
• Evacuations were carried out
• First wave arrived at 11:39 p.m. (CA time)
– About 4 hours after the earthquake
– Rose to a height of only 1 meter in the harbor
• Second wave at 12:30 a.m.
• Third at 12:45 a.m.
Crescent City (continued)
• Fourth at 1:40 a.m.
– This was the largest and most damaging —
22 feet (6 meters) high
– People returned after first two and were engulfed
• Damage
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Destruction of several hundred buildings
Killed 11 people
23 boats sunk or capsized
54 homes destroyed
Fires started when 5 oil storage tanks ruptured
Seiches and Liquefaction
• Triggered in many water bodies in Alaska
• Recorded in rivers, harbors, channels, lakes, and
swimming pools as far away as the Gulf Coast
• Liquefaction
– Major destruction
– Turnagain Heights
Lisbon, Portugal
Basic Data
• November 1, 1755
– All Saints Day
– Many people in stone churches
• Epicenter generally placed about 100 km west of Lisbon
• Richter estimates magnitude at 8.5 to 8.75
• Maximum intensity
Basic Data
• Loss of life in Lisbon alone is placed at 60,000
• Huge area affected
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Destructive intensity in Portugal and most of Spain
Violent shaking in Morocco
Actual shaking of the ground felt by people as far northwest as Germany
Outer limit of damage—600 km
Outer limit of perceptibility—2,000 km
Outer limit of seiches—3500 km
Effects
• Tsunami
– Only great tsunami reported from the Atlantic Ocean
– Reached the city of Lisbon about 10 am, 20 minutes after the
local shock
– Height of 20 ft at many places along Portuguese coast;
maximum 50 feet
– Died out rapidly in Mediterranean
– Reached English Channel disturbing
– Detected in Holland
More Effects
• Seiches
– Over much of western Europe
– Most distant in Scandinavia and Finland
• Fire
– As in many great earthquakes, this caused much of the damage
Izmit, Turkey, 1999
Izmit, Turkey Earthquake
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August 17, 1999, 3:01 a.m. local time
Moment Magnitude: Mw =7.4
Surface Wave Magnitude: Ms=7.8
Body Wave Magnitude: Mb =6.3
Duration Magnitude: Md=6.7
Rupture length of 110 km
Displacements of 2.5 to 3 meters
Maximum displacement of 4.9 meters
Izmit, Turkey
• Deaths—15,135 counted, with a similar number reported
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as missing
Hospitalized—24,000
Houses damaged beyond repair—120,000
Collapsed houses—50,000
People needing housing—600,000
Aftershocks
Monetary Losses
• Industrial Facilities— 2 billion US$
– Majority insured
– Insured value—about 15 billion US$
• Buildings—5 billion US$
– About 8% covered by insurance
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Railroads—1 billion US$
Highways—$200,000,000
Ports —$200,000,000
Socioeconomic losses about equivalent to property losses
Total Losses—16 billion US$
– About 7% of GDP
Filling Seismic Gaps