Temporary seismic monitoring of the Sulmona area (Abruzzo, Italy): quality study of microearthquake locations

Abstract

Abstract. Thanks to the installation of a temporary seismic network, a microseismicity study has been conducted in the Sulmona area (Abruzzo, Italy) with the aim of increasing the knowledge of seismogenic potential of existing active faults. In this work the first seven months (from 27 May to 31 December 2009) of recorded data have been analysed, over a total period of acquisition of about 30 months. Using a semi-automatic procedure, more than 800 local earthquakes has been detected, which highlight the background seismicity previously unknown. About 70% of these events have been relocated using a 1-D velocity model estimated specifically for the Sulmona area. Phase readings quality is checked and discussed, with respect to weighting schemes used by location algorithms, too. The integration of temporary network data with all the other data available in the region enable us to obtain a statistically more robust dataset of earthquake locations. Both the final hypocentral solutions and phase pickings are released as online Supplement. Local magnitude values of the newly detected events ranges between −1.5 and 3.7 and the completeness magnitude for the Sulmona area during the study period is about 1.1. Duration magnitude coefficients have been estimated as well, for comparison/integration purposes. Local Gutenberg–Richter relationship, estimated from the microseismic data, features low b value, possibly suggesting that the Sulmona area is currently undergoing high stress, in agreement with other recent studies. The time-space distribution of the seismic activity with respect to the known active faults, as well the seismogenic layer thickness, are preliminarily investigated.