Performance of the Italian strong motion network during the 2009, L’Aquila seismic sequence (central Italy)

Abstract

On April 6, 2009, the town of L'Aquila in the Abruzzo region (central Italy) was struck by a seismic event at 01:32 (UTC), of magnitude M W = 6.3. The mainshock was followed by a long period of intense seismic activity and within seven days after the mainshock there were seven events of magnitude M W ≥ 5 that occurred from April 6 to April 13. This long seismic sequence was characterized by a complex rupture mechanism that involved two major normal faults of the central Apennines: the Paganica and the Gorzano faults. The strong-motions of the mainshock were recorded by 64 stations of the Italian Strongmotion Network (RAN) operated by the National Civil Protection Department (DPC). Six stations of a local strong-motion array were working in NW L'Aquila suburb area. One of them, located at about 6 km from the Paganica fault surface tip-line, set up in trigger mode, recorded continuously for more than 20 min the mainshock and the aftershocks. Besides the mainshock, the RAN stations recorded in total 78 foreshocks and aftershocks of M L ≥ 3.5, during the period from January to December 2009. The corresponding waveforms provide the most extensive digital strong ground motion data set ever recorded in Italy. Moreover, the 48 three-component observations of events of magnitude M W ≥ 5, recorded at a distance less than 15 km from each of the major involved faults, provide a significant increasing of near-field records available for the Italian territory. Six days after the mainshock, the strongmotion dataset, referred to preliminary locations of the events with M 123 40 Bull Earthquake Eng (2011) 9:39-65 are described. In addition the role of the temporary network that represents an extension of the permanent Italian strong-motion network, supporting the emergency response by civil protection authorities and improving the network coverage has been evaluated.

Frequency variation in site response as observed from strong motion data of the L’Aquila (2009) seismic sequence

“…The Aterno Valley Array, operated by the Italian civil protection, provided recordings of background seismicity since 2000, as well as the recordings of the foreshocks, the mainshock and the aftershocks of the 2009 seismic sequence. A description of the array and of the characteristics of the recordings can be found in Zambonelli et al (2010) and Ameri et al (2009), while a detailed description of the temporary network deployed by several European research institutions is provided by Bergamaschi et al (this volume).…”

Improving ShakeMap performance by integrating real with synthetic data: tests on the 2009 M w = 6.3 L’Aquila earthquake (Italy)

“…The earthquake was very well instrumented by the digital permanent seismic stations of the Italian National Seismic Network of INGV (Amato and Mele 2008), by several broadband stations of the MedNet network (Mazza et al 2008), and by 64 Italian strong motion network (RAN) operated by the National Civil Protection Department (Zambonelli et al 2011). Seven stations (AQG, AQA, AQV, AQM, AQF, AQP, and AQK) were installed in L'Aquila municipality belonging to the RAN strong motion array of "Valle dell'Aterno" to investigate site effects due to the presence of deep sedimentary basin and shallow sedimentary deposits and to assess the spatial variability of earthquake ground motion (Zambonelli et al 2011). The "Valle dell'Aterno" array recorded high peaks of accelerations and specifically 0.68 g (AQV), 0.51 g (AQG), 0.49 g (AQA), and 0.37 g (AQK) at a station close to L'Aquila urban area (Zambonelli et al 2011).…”

The Role of Site Effects at the Boundary Between Seismology and Engineering: Lessons from Recent Earthquakes

“…This was the case of the 2009, L'Aquila earthquake when the Italian department of Civil Protection did not distribute the recording of main shock at AQM station. The accelerometer, set to 1 g full-scale, saturated due to a partial detachment of the instrument from the pillar (Zambonelli et al 2011); In other cases, problems with the recordings were encountered as listed in the following.…”