RU DST-UNITS: Fast moment magnitude estimation and ShakeMaps computation in the Southeastern Alps

In the framework of Project INGV-DPC S3 (2007-2009), a stable and automatic method is implemented at DST to estimate in real time the seismic moment, moment magnitude and corner frequency from broad-band and accelerometric data. The procedure has two steps: the first one consists in interfacing with the Antelope system from where waveforms are retrieved. The real-time waveforms come from the transfrontier network which integrates the Friuli Venezia Giulia (DST, OGS), Austrian (ZAMG) and Slovenian (ARSO) networks. The second step consists in estimating the seismic moment and the corner frequency following Andrews method (1986). At the end the results are stored in a database table. The procedure is tested with the recordings of some strong earthquakes: Carnia 2002 (Mw=4.9), Bovec 2004 (Mw=5.1), Parma 2008 (Mw=5.4) and Aquila 2009 (Mw=6.1), some its aftershock and those of some minor events occurred in the SE Alps area, for which independent seismic moment and Mw estimates, obtained by waveform inversion, are available. The real-time procedure is running at DST and the results are visible on the web page www.dst.units.it/RAF06. The Mw computation together with the moment tensor estimation (TDMT) will also provide better input data for the real-time ShakeMap computation. At DST the “ShakeMap” software has been implemented for the SE Alps area to obtain a stable interface with “Antelope” acquisition system in order to extract the ground motion parameters from waveforms and to generate ShakeMaps within five minutes of the earthquake occurrence. The “ShakeMap” software has been regionally calibrated by adopting a specific near-surface geological classification, different GMPEs for weak and strong motion, and the relationship proposed by Faccioli and Cauzzi (2006) to compute the instrumental intensity. The model is validated by comparing the observed intensity maps data with the instrumental intensities derived from the related scenarios calculated for three important past seismic events in the studied area (Cansiglio 1936, Friuli 1976, Bovec 1998). The computation of the intensity misfit value gives satisfactory results. Finally, an automatic procedure has been developed to exchange in real-time the ground motion parameters with INGV and the other partners of the INGV-DPC S3 project. The results are posted automatically on the department web pages (www.dst.units.it/RAF06).