Want to stay on top of all the space news? Follow @universetoday on TwitterAlaska earthquakes are fairly regular happenings. According to the United States Geological Survey there have been 309 earthquakes ranging from 1.2 to 5.1 on the Reichter scale in the last ten days(March30 to April 7, 2010). Many have been centered around or below Mt. Redoubt. As the volcano becomes slightly more active, the earthquakes will continue and may increase in strength.
The most powerful earthquake in known Alaskan history occurred on March 27, 1964. It registered a 9.2 on the Reichter scale and lasted for over three minutes. Between the quake and the tsunami that followed, 128 people lost their lives. The financial loss totaled over $311 million. The epicenter was 120 km away from Anchorage, but nearly 30 blocks of the city were damaged to varying degrees. The tsunami caused damage along the coast of Alaska, the western coasts of Canada and the United States as well as reaching the Hawaiian Islands. The highest peak of the wave was recorded at 67 meters.
Many of the earthquakes in Alaska are centered around or caused by volcanic activity at Mt. Redoubt. Active for millennia, Mount Redoubt has erupted five times since 1900(1902, 1922, 1966, 1989 and 2009). The eruption in 1989 spewed volcanic ash to a height of 14,000 m. The ash blanketed an area of about 20,000 square km. The 1989 eruption is also notable for being the first ever volcanic eruption to be successfully predicted by long-period seismic events developed by Bernard Chouet. Earthquake and volcanic activity have been reported as recently as noon on April 7, 2010. Scientist believe that the tremors, ash, and steam may be a sign of an impending eruption.
There have been thousands of Alaska earthquakes. The United States Geological Survey keeps track of them here. Try this link for more details about the earthquake disaster of 1964. Here on Universe Today we have a great article about Mt. Redoubt. Astronomy Cast offers a good episode about the plate tectonics that cause earthquakes.