A temporary seismic monitoring of the Sulmona area (Abruzzo, Italy) for seismotectonic purposes.

The seismogenic potential of active faults in the Abruzzo region of central Italy has been tragically brought to the general attention by the April 6, 2009 L'Aquila earthquake. In this region, a system of SW-dipping normal faults has been active both in historical and recent times, with at least three moderate-to-large earthquakes (Avezzano 1915, Barrea 1984, and L'Aquila 2009) and several minor seismic sequences. Some highly populated areas, like the Sulmona basin at the hanging wall of the Mt. Morrone fault (a segment capable of releasing destructive earthquakes, M-max similar to 6.7), have not experienced significant earthquakes in the last millennium; the time lapse since the last event should therefore be comparable with the recurrence time assigned to this fault, enhancing its contribution to seismic hazard in a time-dependent perspective. With the aim of increasing our knowledge on the active deformation pattern, geometry and seismogenic depth of the potential structures by means of low-magnitude seismicity, a bulk of temporary seismometric stations has been installed in the Sulmona area. The small network is managed by OGS (Istituto Nazionale di Oceanografia e Geofisica Sperimentale) and GeosisLab (Chieti-Pescara University) and it consists of six mobile stations set in continuous recording mode and local data storage. The data processing consists in the recognition on the continuous recordings of local events, undetected by the permanent Italian seismic network managed by INGV (Istituto Nazionale di Geofisica e Vulcanologia), and in the location of these small events. Event identification during an ongoing seismic sequence (in our case the 2009 L'Aquila one) is not easy; when the processing of manual pickings is completed, we expect the temporary seismic network to lower the magnitude of completeness in the Sulmona area by about 1 degree, to M<1 events, with significant advantages for studies with seismotectonic and seismic hazard purposes. Some preliminary results on the quality of the seismic recorded data from May 27 to July 15, 2009 and on their spatial distribution are presented.