Rita de Nardis1,3,
RESPONSIBLE SCIENTIST: Enrico Priolo2
1Geosislab, Università "G. d'Annunzio", Chieti Scalo (CH)
2Centro Ricerche Sismologiche, Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Cussignacco (UD) e Sgonico (TS)
3Dipartimento della Protezione Civile, Roma
The seismogenic potential of active faults in the Abruzzo region of central Italy has been severely pointed out by the April 6 2009 L'Aquila earthquake. In this region, a system of southwest-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, Mmax~6.7), have not experienced relevant earthquakes in the last millennium; the elapsed time 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 temporary network of Sulmona is managed by OGS (Istituto Nazionale di Oceanografia e Geofisica Sperimentale) and GeosisLab (Chieti University). It consists of six sites, equipped with portable sismological stations set in continuous recording mode and local data storage. The sites are equipped with six 24 bit acquisition units Reftek 130 (2 of them with 6 channels); four sites are equipped with short-period seismometers Lennartz 3D Light 1s, while two sites are equipped with both a broad band seismometer Guralp CMG40 and accelerometer Kinemetrics FBA ES-T each (Table 1).
Figure 1. Map of the temporary seismometric network deployed in the area of Sulmona (L'Aquila, Italy). Left: general overview; right: detail of the area.
Table 1 Main characteristics of the Sulmona network.
The network has been deployed on May 2009 and it is still in operation. During its life, the layout of the network has slightly changed in order to improve the quality of the recorded signals. In particular, four stations of the six stations moved in nearby, better locations, and consequently their name was changed (e.g. SL01 was moved to SLA1, and similarly for theother cases). Moreover, the continuous data of two stations of the Seismic National Network managed by INGV (i.e. LPEL and INTR) have been included in the analysis.
The dataset of events identified from May 27 to December 31, 2009 in the study area ---this area does not include the area of L'Aquila, about 50 km away--- has more than 830 entries, of which 550 have been localized (Fig. 2), and it increases the number of earthquakes available catalogue (ISIDE-INGV) by an order of magnitude.
Figure 2. Map of the seismicity detected by the Sulmona temporary network. Stations are marked by a cross. Two of the stations belong to the National Seismic Network managed by INGV.
Acknowledgements - Stations LPEL (Lama dei Peligni) and INTR (Introdacqua) belong to the National Seismic Network managed by INGV. The continuous waveform data of these stations have been kindly provided by the Centro Nazionale Terremoti.