Evaluation of the recorded ground motions for the unusual earthquake of 13 August 2006 (M (w) 5.3) in Michoacan M,xico

摘要

The focal mechanism of the moderate earthquake of 13 August 2006 M (w) = 5.3, which occurred in the border coastal area between Michoacan and Colima, M,xico, is unusual. As shown by the Global Centroid Moment Tensor (CMT) project and the Servicio Sismolgico Nacional de Mexico (SSN), the thrust mechanism is striking almost perpendicularly to the majority of earthquakes occurring along the subduction zone of the Mexican Pacific continental margin which commonly strike nearly parallel to the trench. The purpose of this study is to analyze the observed ground motions of this particular event relative to those of the common events. First, we apply the H/V technique to verify that the stations involved in this study are nearly free of site effects. Then, we compare the observed ground motions with (i) three empirical ground motion prediction equations (GMPEs) appropriate for the region, (ii) ground motions of four real earthquakes with the common mechanism, and (iii) the Fourier spectrum of a selected common event.