An imaging technique for subsurface faults using teleseismic-wave records II: Improvement in the detectability of subsurface faults

We have developed an imaging algorithm for subsurface faults on the basis of the steepest descent method in our previous paper. In this paper we introduce two new techniques, the multi-event stacking and multi-master stacking, to improve detectability for subsurface faults. The multi-event stacking is a technique using data from plural earthquakes with different incident angles. The multi-master stacking is a technique using data of a single earthquake, in which the images obtained by employing different master receiver are stacked. We examined the feasibility of our approach using several trial models and synthetic data with different signal to noise ratios, different pulse durations and different incident angles in the two dimensional SH cases. In the numerical experiments, we could recover the image of the subsurface fault for all the trial models used, which indicates our method has a potential for sensing real subsurface faults.