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

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 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 de- tected, 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 Sul- mona 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 de- tected events range between −1.5 and 3.7 and the complete- ness magnitude for the Sulmona area during the study period is about 1.1. Duration magnitude coefficients have been es- timated as well for comparison/integration purposes. The lo- cal Gutenberg–Richter relationship, estimated from the mi- croseismic data, features a low b value, tentatively suggest- ing 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 thick- ness are preliminarily investigated.