From earthquake centroid to spatial-temporal rupture evolution: Mw 6.3 Movri Mountain earthquake, June 8, 2008, Greece

Abstract

We propose a new strategy to reveal the spatialtemporal evolution of the earthquake rupture process from near-regional data, without assuming a constant rupture velocity. The approach is based on a conjugate gradient method, for which we express analytically the required waveform-misfit derivative with respect to slip on the fault. The derivative is given by back-propagation of residual seismograms towards the source. A good initial source approximation is necessary, being obtained from hypocenter location and centroid-moment tensor solution. The iterative approach then gradually reveals major characteristics of the source process. As an application, we investigate a line source model of a damaging Mw6.3 earthquake in Greece, revealing predominantly unilateral rupture propagation and two or three main slip patches, one of which being significantly delayed, indicating a temporary rupture arrest. The region of largest slip coincides with the region of least abundant aftershocks between hypocenter and centroid. The method has application potential for shakemaps, emergency response, and/or aftershock hazard assessment. Copyright 2009 by the American Geophysical Union.