Earthquake in Alaska: M6.4 Quake Strikes November 12, 2012


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Seismic History of Alaska

Seismic activity in Alaska for the 30 days prior to the November 12 earthquake – Image credit USGS

This map of current seismicity over the past month shows that Alaska is no stranger to major earthquakes and, if Aleutian Islands to the west are included, the tremor of November 2012 may be considered relatively minor.

A look at the USGS’s list of historic earthquakes for the state shows over 60 of at least M5.0, of which six had a magnitude of at least M8 – almost 40 times larger than the most recent event and releasing a staggering 250 times more energy (the magnitude scale is logarithmic).

In 1964, the city of Anchorage was the location of the second largest tremor ever recorded worldwide.

At M9.2 it was larger than the deadly events in Japan in 2011 or Sumatra in 2004 and second only to the M9.5 which occurred off Chile in 1960.

Like many other major tremors it generated a tsunami, though in fact relatively few lives were lost given the scale of the energy released – 120 people were reported killed, compared with many thousands in other, smaller, events.

Alaska Earthquakes

Considering its tectonic setting and the high risk of major earthquakes under which it lies, Alaska has escaped the most recent event unscathed (an M7.8 further south in the same fault in Canadian waters on 28 October 2012 similarly caused little damage and no loss of life) and can expect many more tremors on the scale of that of November 2012.


Haeussler, P.J. and Plafker, G. Earthquakes in Alaska. (2012). Accessed November 13, 2012.

USGS. Historic earthquakes listing. (2012). Accessed November 13, 2012.

USGS. M6.4 248 km s of Cape Yakataga. (2012). Accessed November 13, 2012.

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