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

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 7 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 have been detected, which highlights the previously unknown background seismicity. About 70% of these events have been relocated using a 1-D velocity model estimated specifically for the Sulmona area. The integration of temporary network data with all the other data available in the region enables us to obtain a statistically more robust data set of earthquake locations. Both the final hypocentral solutions and phase pickings are released as a supplement; an appendix also describes phase readings' quality with respect to weighting schemes used by location algorithms. Local magnitude values of the newly detected events range 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. The local Gutenberg-Richter relationship, estimated from the microseismic data, features a low b value, tentatively suggesting that the Sulmona area may be currently undergoing high-stress conditions, 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.