Source Rupture Process of the Tecoman, Colima, Mexico Earthquake of 22 January 2003, Determined by Joint Inversion of Teleseismic Body-Wave and Near-Source Data

Abstract

The spatial and temporal slip distribution of the Tecoman, Colima, Mexico earthquake is estimated from near-source strong-motion and teleseismic body-wave data. To perform a stable inversion, we applied smoothing constraints and determined their optimal relative weights on the observed data using an optimized Akaike's Bayesian information criterion (ABIC). The source parameters are as follows: (strike, dip, slip) = (300°, 20°, 93°), seismic moment M = 2.3 × 1020 N m; source duration = 30 sec; along-strike distance = 35 km; along-dip distance = 70 km. We found that the rupture process can be divided into three stages: the rupture nucleated near the hypocenter (stage I), then it broke the first asperity centering about 15 km southwest from the epicenter (stage II); and the rupture propagated to the northeast and the second asperity was broken (stage III). We also estimated the shear-stress change due to the rupture process of the mainshock on and around the major fault zone. It appears that one cluster of aftershocks for the first 5 days, which took place in and adjacent to the zones of stress, increased due to the fault rupture during the mainshock, but overall correlation between the aftershock location and the stress pattern is not clear. Manuscript received 14 May 2003.