Improvement in earthquake location accuracy from minimum 1-D velocity model: an example from Gioia Tauro Basin (southeastern Calabria, ITALY)

We computed a 1-D velocity model in the Gioia Tauro Basin area (southwestern Calabria, Italy) by inverting P-wave arrival times recorded by local seismic network consisting of eleven stations. For this purpose we used a data set of 207 local earthquakes which were located with a minimum of 7 arrivals, a travel time residual (rms) 0 .3 s and an azimuthal gap 180º. This “Minimum 1-D velocity model” is complemented by station corrections which are influenced by near-surface velocity heterogeneity. Using the new P-wave velocity model and the program HYPOELLIPSE, we relocated the 207 selected events. Tests were carried out to verify the robustness of inversion results in order to corroborate the conclusions drawn from our findings. The comparison between previous and present earthquake locations has shown a significant improvement. The obtained “Minimum 1-D velocity model” may strongly help in the future routine earthquake location in the area.