Abstract

I have relocated seismicity occurring in the St. Elias, Alaska, region between 1973 and 2002 to examine its relation to the 1979 MS 7.1 St. Elias mainshock and compare the relocations to recent studies of Global Positioning System (GPS)/geodesy, structural geology, geothermometry, and marine geophysical studies. The relocated seismicity clearly shows that much of the seismic deformation is occurring on or above a regional decollement that may be located at the top of the basement of the Yakutat microplate. A persistent Y‐shaped concentration of seismicity located east and north of Icy Bay contains the deepest (15–30 km) earthquakes within the region and reflects the present‐day deformational front between the Yakutat microplate and southern Alaska. Coulomb failure stress modeling suggests that static stress changes had little influence on the location of most aftershocks of the 1979 sequence.

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