Rapid aseismic moment release following the 5 December, 1997 Kronotsky, Kamchatka, earthquake

Abstract

Model inversions of displacements of continuously operating GPS stations in Kamchatka show that aseismic afterslip during 2 months following the Mw,=7.8, 5 December, 1997 Kronotsky subduction earthquake released as much moment as the earthquake itself. The rapidly decaying transient slip on the subduction underthrust occurred near the downdip edge of the coseismic rupture and extended laterally away from it, including a region of vigorous foreshock activity. A logarithmic decay function fit to the cumulative afterslip curve has a relaxation time of about 3 days. Rapid afterslip can contribute significantly to the moment release of partially coupled subduction zones.