Earthquake News

Rats Island Earthquake February 04, 1965 M 8.7

Earthquake in Rats Islands, February 4, 1965, M 8.7

The 1965 Rat Islands earthquake struck on February 4 at 05:01 UTC (19:01, 3 February local time). It had an 8.7 magnitude and created a tsunami on Shemya Island that was nearly 10 meters high, however it did very little damage.

The Aleutian Islands, a group of volcanic islands forming an island arc as a result of the subduction of the Pacific Plate beneath the North American Plate, include the Rat Islands. There have been numerous mega thrust earthquakes at this plate boundary, known as the Alaska-Aleutian mega thrust.

Alaska's tectonics and seismicity are depicted on a map.

The 1963 Kuril Islands earthquake, the 1964 Alaska earthquake, and the 1965 Rat Islands earthquake all have characteristics in common.

Earthquake
Based on the pattern of the aftershocks, the rupture along the plate boundary that caused the earthquake was 600 km long.
Three asperities at the plate contact, each causing a pulse of moment release, are suggested by the pattern of energy release. The concept that the earthquake was composed of three sub-events linked to three structural "blocks" within the overriding plate is supported by modeling of the tsunami.

Nearly two months after the initial shock, a 7.6-magnitude earthquake that also caused a minor tsunami struck. This event, which was brought on by the previous one and occurred on a normal fault within the subducting plate's outer rise, was not an aftershock.

Tsunami
On Shemya Island, the tsunami's maximum run-up height was 10.7 meters, compared to 2.0 meters on Amchitka Island, 1.6 meters on Attu Island, and 1.1 meters in northern Kauai, Hawaii. Additionally, it was noted in eastern Russia, Japan, California, Peru, Ecuador, Mexico, and Ecuador.

Damage
On Amchitka Island, flooding from the tsunami caused $10,000 in damage. Runway fractures were a minor symptom of the earthquake on both the Attu and Shemya islands.

 

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