Largest US Quake since 2002.
Posted by JAC on 6/24/2011, 7:30 am
A major earthquake of M 7.2-7.6 hit the Fox Islands in the Alaskan Aleutian Chain today.

This is the strongest earthquake recorded in the United States in the western hemisphere since the great Denali, Alaska earthquake on November 3, 2002 of M 7.9.

The only other regional earthquake of larger magnitude in the past 20 years was an M 7.0 in the Andreanof Islands on June 10, 1996.

It is the strongest earthquake in this region of the Fox Islands since an M 7.2 on March 9, 1957 but the last event of larger magnitude occurred 82 years ago on March 7, 1929 with M 8.6.

Earthquakes similar to today's occurred on April 18, 1916, September 8, 1909 and December 31, 1901.

It is also the strongest earthquake in the world since the great M 9.0 in Japan on March 11.

A tsunami warning was initially declared but later cancelled.

The earthquake was in a remote region but earthquakes in this region in the past have produced tsunamis directed towards Hawaii, so the tsunami warning was justified and a small tsunami may still be observed in Hawaii.

Residents of small coastal towns in the Aleutians were sent to higher ground but no tsunami materialized.

NEIC reported the earthquake was felt with intensity V in Nikolski about 250 km from the epicenter and with intensity II as far away as 1500 km in Anchorage and Elmendorf AFB.

More believable intensities II were reported from Unalaska and Dutch Harbor, Alaska.

A resident in Adak reported shaking and rumbling from the quake for about 20 seconds.

It was reported felt throughout the Central Aleutians.

The following picture shows Adak Island about 200 km to the west of the Fox Islands






The immediate trigger for this event was probably a change in the geomagnetic field caused by the CME which hit the ionosphere several minutes (around 03:00 UT) before the Fox Islands earthquake.






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Full Halo CME - Earth Directed - JAC, 6/21/2011, 5:18 am
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