Testing the stability of moment tensor solutions for small earthquakes in the Calabro-Peloritan Arc region (southern Italy)

摘要

The aim of this study is to test the stability of moment tensor solutions for crustalearthquakes in the Calabro-Peloritan area (southern Italy). We used waveformsrecorded by the Italian National Seismic Network managed by the IstitutoNazionale di Geofisica e Vulcanologia and the CAT-SCAN (Calabria ApennineTyrrhenian - Subduction Collision Accretion Network) project. We computed themoment tensor solutions using the Cut And Paste (CAP) method. The techniqueallows the determination of the source depth, moment magnitude and focalmechanisms using a grid search technique. For the earthquakes investigated, wetried different station distributions and different velocity models. Results were alsochecked by computing the moment tensor solutions using the SLUMT grid-searchmethod. Both methods (CAP and SLUMT) allow time shifts between synthetic andobserved data in order to reduce the dependence of the solution on the assumedvelocity model and on earthquake location errors. Comparisons have been madewith the available published solutions. The final focal mechanisms were robustlydetermined. We show that the application of the CAP and SLUMT methods canprovide good-quality solutions in a magnitude range not properly represented in theItalian national earthquake catalogues, and where the solutions estimated from Ponsetpolarities are often poorly constrained.