Analisi di sequenze sismiche che si verificano lungo l'appennino Campano-Lucano

The topic of this study is the characterization of seismic sequences that occur along the Campania-Lucania fault system. This area is monitored by the high density seismic network ISNet, which consists of 31 seismic stations spread along the fault system that generated the 1980 Irpinia earthquake. Since the network is operational, it produced a seismic catalog of more than 2000 events. In this study I identified the sequences occurred over the period 2008 ¿ 2012, starting from the event bulletin of the network. To this purpose, the seismic events that constitute the sequences were automatically identified by a cross-correlation algorithm, that continuously scanned the helicorder and extracted the traces according to a similarity criterion. With this procedure, even negative magnitude events otherwise undetectable by visual inspection were extracted from the continuous records. For each event I calculated the source parameters: magnitude, seismic moment, corner frequency, and size of the source. Moment magnitude and corner frequency were estimated assuming an omega-square decay of the S-wave spectra; source size and stress drop derived by the use of the Brune model for a circular rupture. We found that self-similarity holds, but with a stress drop larger than the average estimates in the area. Furthermore, the distribution of events for magnitude was studied and the parameters of the Gutenberg ¿ Richter law calculated. Finally, throughout a high-resolution location of the identified events, the intra-sequence and inter-sequences evolution of the events was studied, using statistical models to understand the distribution in magnitude, distance and time of the events.