GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 2.1 315 of 87 events (266 records) in the time-span 1972-2004; Caprio et al. (2015) provided an Italian regional estimation of the GMICEs starting from the same dataset. In this study, we extend the approach proposed by Faenza and Michelini (2010) by carrying out the calculation of GMICEs on more ground motion parameters than Peak Ground Acceleration and Velocity (PGA, PGV) alone. It is known that the damaging potential of an earthquake does not reside in the shaking amplitude alone, so we make a preliminary selection of other parameters which could better describe different seismic features, such as duration, released energy and frequency content. Calculations are carried out over eight GMPs in total: PGA, PGV, Peak Ground Displacement (PGD), Arias and Housner intensities, and pseudo spectral acceleration at 0.3, 1.0 and 3.0 seconds (PSA 03 , PSA 10 , PSA 30 ). Our aim is to keep the GMICEs used for the Italian territory as reliable and updated as possible, also searching for GMPs that possibly show a better correlation to MI than PGA alone. We first expand a re-elaborated version of the Faenza and Michelini (2010) database with high quality accelerometric data regarding 25 events (124 records) occurred in the time- span 2002-2016 in Italy and Slovenia (Tiberi et al. , 2018). Part of the data is taken from the Italian accelerometric database ITACA (Luzi et al. , 2008), and belongs to the RAN (Rete Accelerometrica Nazionale) network (Gorini et al. , 2010; Costa et al. , 2015), managed by the Italian National Civil Protection. The most recent, high quality data is collected by CE3RN (Central Eastern European Earthquake and Research Network) (Costa et al. , 2010; Bragato et al. , 2014) and RAN stations. Macroseismic intensity data-points are taken from the Italian Macroseismic Database (DBMI15, DBMI11) and from the macroseismic archive for the Slovenian events (ARSO, 2012). We derive two sets of empirical conversion equations between each of the selected parameters and MI: the first one using the Linear Least Squares technique and the second one using Orthogonal Distance Regression. Finally, we determine which method provides the best results and which parameters seem to better estimate the observed intensity in terms of R 2 of the obtained regression law, and we test the stability of the derived GMICEs using 3-fold cross-validation. Our MI data, expressed in MCS scale and binned into classes at 0.5 intensity intervals, is distributed from 2 to 8, so this is the intensity range in which extracted laws are expected to be valid. We believe that the growing availability of observed intensity data will allow for ulterior improvement and validation of GMICEs for the Italian territory; in particular, another statistically significant set of independent data would provide to be useful for testing. Furthermore, in order to better describe damages in near fault areas, a more focused study is needed to find a combination of the most significant ground motion parameters in order to take into account seismic features other than peak amplitude values, as is current use, hopefully providing important improvements in near real-time identification of major damaged areas. Acknowledgements. The authors wish to express their grateful thanks to the National Civil Defence of Rome for the data used in this study. We would also like to show our gratitude to Ina Cecić for sharing the precious Slovenian macroseismic data that helped us enrich our dataset. Macroseismic data and Resources. ARSO 2012 macroseismic archive. Agencija Republike Slovenije za Okolje, Ljubljana, Slovenia, Electronic database. The Italian Macroseismic Database DBMI11 (Locati et al. , 2011) for the seismic events until 2002: http://emidius.mi.ingv.it/DBMI11/ (last accessed July 2016). The Italian Macroseismic Database DBMI15 (Locati et al., 2016) for the seismic events from 2003 until 2014: http://emidius.mi.ingv.it/ DBMI15/ (last accessed March 2017) References Bragato P. L., Costa G., Gallo A., Gosar A., Horn N., Lenhardt W., Mucciarelli M., Pesaresi D., Steiner R., Suhadolc P., Tiberi L., Živčić M. and Zoppè G.; 2014: The Central and Eastern European Earthquake Research Network- CE3RN . Geophys. Res. Abstracts, 16 , 13911. Caprio M., Tarigan B., Worden C. B., Wiemer S. and Wald D. J.; 2015: Ground Motion to Intensity Conversion Equations (GMICEs): A Global Relationship and Evaluation of Regional Dependency . Bull. Seism. Soc. Am., 105 , 3, 1476-1490. DOI 10.1785/0120140286.