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Largest Earthquakes in the US

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A Train thrown down by the San Francisco earthquake of April 18, 1906

A Train thrown down by the San Francisco earthquake of April 18, 1906

In the US, Alaska is the most earthquake-prone state and one of the most seismically active regions in the world. Alaska experiences a magnitude 7 earthquake almost every year, and a magnitude 8 or greater earthquake on an average of every 14 years.

The largest recorded earthquake in the United States was a magnitude 9.2 quake that struck Prince William Sound, Alaska on Good Friday, March 28, 1964 UTC. Each year the southern California area has about 10,000 earthquakes. Most of them are so small that they are not felt. Only several hundreds are greater than magnitude 3.0, and only about 15-20 are greater than magnitude 4.0.

From 1975-1995 there were only four states in the US that did not have any earthquakes. They were: Florida, Lowa, North Dakota, and Wisconsin. Earthquakes occur in the central portion of the United States too! Some very powerful earthquakes occurred along the New Madrid fault in the Mississippi Valley in 1811-1812. The largest recorded earthquake in the worldwas a magnitude 9.5 in Chile on May 22, 1960.

Listed below are a few of the largest earthquakes that occurred in the US.

1. Alaska Earthquake (Montague Island in Prince William Sound)

Date: March 28, 1964

Time: 03:36 UTC

Fatalities: 128 lives (tsunami 113, earthquake 15)

Property loss: $311 million

Magnitude: 9.2

Details of the incident:

This Alaskan Earthquake of March 28, 1964 uplifted the sea floor at CapeCleare on MontagueIsland in Prince William Sound. This is the area of the greatest recorded tectonic uplift on land (33 feet). The earthquake was accompanied by a vertical displacement over an area of about 520,000 square kilometers which ranged from about 11.5 meters of uplift to 2.3 meters of subsidence relative to sea level. This shock also generated a tsunami that devastated many towns along the Gulf of Alaska, and left serious damage at Alberni and Port Alberni, Canada, along the West Coast of the United States, and in Hawaii. The maximum wave height recorded was 67 meters at Valdez Inlet. This great earthquake and ensuing tsunami took 128 lives (tsunami 113, earthquake 15), and caused about $311 million in property loss. This earthquake affected many towns including Anchorage, Chitina, Glennallen, Homer, Hope, Kasilof, Kenai, Kodiak, MoosePass, Portage, Seldovia, Seward, Sterling, Valdez, Wasilla, and Whittier.

2. Andreanof Islands, Alaska (Aleutian Tsunami)

Date: March 9, 1957

Time: 14:22 UTC

Property loss: $5 million (in 1957)

Fatalities: None

Magnitude: 8.3

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Details of the incident:

On March 9, 1957, at 14:22 UTC, an earthquake occurred south of the Andreanof Islands, in the Aleutian Islands of Alaska. The earthquake destroyed two bridges on AdakIsland, damaged houses, and left a 4.5 meter crack in a road. MountVsevidof erupted after being dormant for 200 years. This earthquake triggered a tsunami across the pacific. No lives were lost and the Hawaiian Islands suffered the greatest with damage costs approximately $5 million dollars. bridges were destroyed and sections of highways were flooded at Haena in Hawaii and waves reached a height of 16 m. Houses were washed out and destroyed at Wainiha and Kalihiwai. The Coconut Island In Hilo Bay, was covered by 1 m of water and the bridge connecting it to shore was destroyed.

The tsunami also caused minor damage in San Diego Bay, California, and also travelled to distant countries such as Chile, El Salvador, Japan, and other areas in the Pacific region. More than 300 aftershocks were reported along the southern edge of the Aleutians, from Unimak Island to AmchitkaPass.