Rupture of Denali fault responsible for 7.9-mag Alaskan earthquake

Geologists just back from a reconnaissance of the 7.9-magnitude Alaska earthquake of November 3 confirm that rupture of the Denali fault was the principal cause of the quake. According to Caltech geology professor Kerry Sieh, Central Washington University geological sciences professor Charles Rubin, and Peter Haeussler of the U.S. Geological Survey, investigations over a week-long period revealed three large ruptures with a total length of about 320 kilometers. The principal rupture was a 210-kilometer-long section of the Denali fault, with horizontal shifts of up to nearly 9 meters (26 feet). This places the rupture in the same class as those that produced the San Andreas fault’s two historical great earthquakes in 1906 and 1857. These three ruptures are the largest such events in the Western Hemisphere in at least the past 150 years.

Alaska Quake Seems to Trigger Yellowstone Jolts

A major, magnitude-7.9 earthquake that rocked Alaska on Sunday apparently triggered scores of earthquakes some 2,000 miles away at Yellowstone National Park in Wyoming. By 8:30 a.m. MST Monday Nov. 4 – about 17 hours after the Alaskan quake – more than 200 small earthquakes had been detected occurring in clusters throughout the Yellowstone area. The quakes were recorded by the Yellowstone seismic network operated by the University of Utah Seismograph Stations.