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 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.