Giulio Selvaggi

ISMD, a Web Portal for Real‐Time Processing and Dissemination of INGV Strong‐Motion Data

Online Material: Earthquake catalog and strong motion stations.nnIn Italy, strong‐motion monitoring started in the early 1970s, when the Rete Accelerometrica Nazionale (RAN, the Italian National Strong Motion Network; http://www.protezionecivile.gov.it/jcms/it/ran.wp; see Data and Resources for a complete listing of all websites listed in this article) was designed and installed by the Agenzia Nazionale per le Nuove Tecnologie, l’Energia e lo Sviluppo Economico Sostenibile (ENEA) and ENEL (an Italian power company). The aim was to evaluate the seismic risk in connection with the construction of nuclear power plants. Since 1997, the RAN (Gorini etxa0al. , 2010) has been run by the Dipartimento della Protezione Civile (DPC). At present, the RAN includes about 500 digital strong‐motion stations.nnThe contribution of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) to Italian strong‐motion monitoring started some years later. Through the 2004–2006 agreement between the INGV and the DPC (Strong‐Motion Stations Project), the INGV began the phase of strong‐motion monitoring (Augliera etxa0al. , 2010, 2011). Since 2006, a complete renewal of the (velocimetric) Rete Sismica Nazionale (RSN; Amato and Mele, 2008) was made by installing accelerometers to sites where broadband RSN velocimeters were already present. Altogether, the current ∼150 high‐dynamics digital strong‐motion stations that cover the Italian territory constitute the INGV strong‐motion network.nnThe first channel chosen by the INGV to disseminate the recorded waveforms was through the European Integrated Data Archive (EIDA; http://eida.rm.ingv.it/; http://www.orfeus-eu.org/eida/eida.html), a web portal devoted to seismic data exchange that was developed in the framework of the Network of Research Infrastructures for European Seismology (NERIES) European project (www.neries-eu.org, Networking Activity 3 [NA3]). Since 2008, the INGV raw signals have been downloadable in the Standard for the Exchange of Earthquake Data (SEED) format from the continuous data archive of the INGV National Earthquake Centre (Centro Nazionale Terremoti, CNT). …

Aseismic transient during the 2010-2014 seismic swarm: evidence for longer recurrence of M ≥ 6.5 earthquakes in the Pollino gap (Southern Italy)?

In actively deforming regions, crustal deformation is accommodated by earthquakes and through a variety of transient aseismic phenomena. Here, we study the 2010–2014 Pollino (Southern Italy) swarm sequence (main shock MW 5.1) located within the Pollino seismic gap, by analysing the surface deformation derived from Global Positioning System and Synthetic Aperture Radar data. Inversions of geodetic time series show that a transient slip, with the same mechanism of the main shock, started about 3–4 months before the main shock and lasted almost one year, evolving through time with acceleration phases that correlate with the rate of seismicity. The moment released by the transient slip is equivalent to MW 5.5, significantly larger than the seismic moment release revealing therefore that a significant fraction of the overall deformation is released aseismically. Our findings suggest that crustal deformation in the Pollino gap is accommodated by infrequent “large” earthquakes (MWu2009≥u20096.5) and by aseismic episodes releasing a significant fraction of the accrued strain. Lower strain rates, relative to the adjacent Southern Apennines, and a mixed seismic/aseismic strain release are in favour of a longer recurrence for large magnitude earthquakes in the Pollino gap.