The New Shakemap in Italy: Progress and Advances in the Last 10 Years

Date: 4/25/2019

Time: 02:30 PM

Room: Pine

We describe the new configuration of the Italian ShakeMap service provided by INGV. It features i.) the adoption of recently developed GMPEs and Vs,30 grid map values for the evaluation of local site effects, and ii.) the adoption of the newly developed USGS-ShakeMap version 4 software. We adopted a subdivision in zones with the same tectonic regime, after the the 2016 Italian seismic hazard model (MPS16, Meletti et al., 2017). The most appropriate GMPEs were selected after performing a ranking of the available and most suited GMPEs for the individual tectonic regions. Notably, we have adopted the new USGS-ShakeMap (v4) software (https://github.com/usgs/shakemap) which relies on the large library of GMPEs modules provided by the OpenQuake platform (https://www.globalquakemodel.org/tools-products). The Italian territory and adjacent areas has been subdivided into 4 tectonic regions - shallow active, deep active, Calabrian subduction and volcanic areas. We have found that the ITA10 (Bindi et al., 2011) fits nicely the data for the shallow active crustal regions; the Bindi et al. (2014) relation is appropriate for the deep active region (depths>35 km); the Abrahamson et al (2016) is adopted for the subduction zone and the Tusa and Langer (2016) is proper for the volcanic areas (Aetna, Aeolian, Vesuvius and Phlegraean Fields volcanos). The Vs,30 map used for site corrections is based on the EC8 soil categories (A, B and C). The new configuration has been validated adopting the leave-one-out approach of comparing the interpolated value at the recording station with that observed. We have used 166 earthquakes for a total of about 9,000 intensity measures. The new configuration reduces significantly the ground motion bias and the number of data outliers with respect to the the original shakemap configuration (Michelini et al, 2008). Finally, the INGV system for the generation of the maps of ground shaking has been renovated to exploit fully the entire data/analysis chain implemented at INGV from the real-time data streams to the revised strong-motion waveforms.

Presenting Author: Alberto Michelini

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