PSI - Issue 44

Pasquale Cito et al. / Procedia Structural Integrity 44 (2023) 3–10 P. Cito, A. Vitale, I. Iervolino / Structural Integrity Procedia 00 (2022) 000–000

9

7

area is about 800 km 2 for

04 PSHA and 600 km

2 for

19 PSHA .

5. Conclusions In this study, the ground motion intensity, from ShakeMap envelopes for the M5+ earthquakes of the 2016-2017 central Italy seismic sequence, were compared to the PSHA results for the hit area, in terms of PGA and   1s Sa T  with 50 and 475 years exceedance return period. For each spectral and return period, the ground motion intensity in the area struck by the sequence was derived from two countrywide seismic hazard maps, which were computed via PSHA using (separately) two different hazard models. One is related to that adopted by the PSHA lying at the basis of the building code in Italy, known as MPS04. The other is based on an average grid-seismicity source model, derived from a set of source models used for a recent PSHA study for Italy, named MPS19. After a brief analysis of the differences between the hazard maps based on these two models, the study investigated how the area subjected to at least one exceedance of the ground motion intensities according to PSHA, estimated using ShakeMap envelopes, varies with the hazard model. The following was found.  The differences between the two hazard models is such that 19 PSHA results, in terms of PGA and   1s Sa T  with 50 r T yr  , are lower than 04 PSHA across almost the whole country, especially in the areas within the MPS04 source zones. For 475 r T yr  , 19 PSHA tends to be lower than 04 PSHA in the moderate-to-high hazardous areas of the country, including the area struck by the 2016-2017 central Italy seismic sequence; in the areas outside MPS04 zones, 19 PSHA results tend to be larger than 04 PSHA .  For the considered vibration and return periods, the estimated area exposed to at least one exceedance is of the same order of magnitude for the considered PSHA models. Such an area is in the 5000-7000 km 2 range for 50 r T yr  and 600-1000 km 2 for 475 r T yr  , depending on the spectral ordinate and the PSHA model. For 50 r T yr  , the absolute difference between the exceedance areas is about 2000 km 2 and 500 km 2 for PGA and   1s Sa T  , respectively; in the case of 475 r T yr  , it reduces to 50 km 2 for PGA and 200 km 2 for   1s Sa T  . Acknowledgements The work presented in this article was developed within the H2020- SC5-2019 Real-time Earthquake Risk Reduction for a Resilient Europe (RISE) project, Grant Agreement 821115. References Beyer, K., Bommer, J.J., 2006. Relationships between Median Values and between Aleatory Variabilities for Different Definitions of the Horizontal Component of Motion. Bulletin of the Seismological Society of America, 96, 1512–1522. https://doi.org/10.1785/0120050210 Bindi, D., Pacor, F., Luzi, L., Puglia, R., Massa, M., Ameri, G., Paolucci, R., 2011. Ground motion prediction equations derived from the Italian strong motion database. Bulletin of Earthquake Engineering, 9(6), 1899–1920. https://doi.org/10.1007/s10518-011-9313-z Bommer, J., Douglas, J., Strasser, F., 2003. Style-of-Faulting in Ground-Motion Prediction Equations. Bulletin of Earthquake Engineering, 1, 171–203. https://doi.org/10.1023/A:1026323123154 Chioccarelli, E., Cito, P., Iervolino, I., Giorgio, M., 2019. REASSESS V2.0: software for single- and multi-site probabilistic seismic hazard analysis. Bulletin of Earthquake Engineering, 17, 1769–1793. https://doi.org/10.1007/s10518-018-00531-x Chioccarelli, E., Cito, P., Visini, F., Iervolino, I., 2021. Sequence-based hazard analysis for Italy considering a grid seismic source model. Annals of Geophysics, 64(2). https://doi.org/10.4401/ag-8586 Cito, P., Iervolino, I., 2020. Rarity, proximity, and design actions: mapping strong earthquakes in Italy. Annals of Geophysics, 63(6). https://doi.org/10.4401/ag-8516 Cornell C. Allin., 1968. Engineering Seismic Risk Analysis. Bulletin of the Seismological Society of America, 58, 1583–1606. CS.LL.PP., 2018. Decreto Ministeriale: Norme tecniche per le costruzioni. Gazzetta Ufficiale della Repubblica Italiana, n.42, 20 febbraio, Suppl. Ordinario n.8 Ist. Polig. e Zecca dello Stato S.p.a., Rome (in Italian). Gruppo di Lavoro., 2004. Catalogo Parametrico dei Terremoti Italiani, versione 2004 (CPTI04), INGV. http://emidius.mi.ingv.it/CPTI/. Iervolino, I., 2016. Soil-invariant seismic hazard and disaggregation. Bulletin of the Seismological Society of America, 106(4), 1900–1907. https://doi.org/10.1785/0120160072 Ambraseys, N.N., Simpson, K.A., Bommer, J.J., 1996. Prediction of horizontal response spectra in Europe. Earthquake Engineering and Structural Dynamics, 25(4), 371–400. https://doi.org/doi:10.1002/[SICI]1096-9845[199604]25:4<371::AID-EQE550>3.0.CO;2-A.