Even if earthquakes occur as time-space clusters, classical probabilistic seismic hazard analysis (PSHA) typically considers only the largest-magnitude event within each cluster; i.e., the mainshocks. This implies assuming that the earthquakes, preceding and following the mainshock in each sequence, that is, foreshocks and aftershocks, respectively, have a negligible effect on the seismic hazard at the construction site. On the other hand, the recent advances of earthquake engineering allow to include aftershocks in the hazard assessment through the so-called sequence-based PSHA (SPSHA). SPSHA modifies the formulation of PSHA and models aftershocks occurrence relying on the modified Omori law. For the United Kingdom (UK), the Omori parameters were recently estimated using a relatively simple procedure, and data from only four sequences. This study investigates the implications, on SPSHA results, of the Omori parameters, considering uniform hazard spectra (UHS) for three sites across the country, characterized by different seismic hazard according to PSHA. It found that, in the UK, the sensitivity of the UHS’ to the parameters choice is limited, whatever the seismic hazard of the site and the exceedance return period, likely because of the generally limited seismic hazard in the country.

A sensitivity analysis of sequence-based seismic hazard assessment for the United Kingdom / Orlacchio, M.; Cito, P.; Iervolino, I.. - (2022). (Intervento presentato al convegno 3rd European Conference on Earthquake Engineering & Seismology tenutosi a Bucharest (Romania) nel 4-9 September 2024).

A sensitivity analysis of sequence-based seismic hazard assessment for the United Kingdom

M. Orlacchio;P. Cito;I. Iervolino
2022

Abstract

Even if earthquakes occur as time-space clusters, classical probabilistic seismic hazard analysis (PSHA) typically considers only the largest-magnitude event within each cluster; i.e., the mainshocks. This implies assuming that the earthquakes, preceding and following the mainshock in each sequence, that is, foreshocks and aftershocks, respectively, have a negligible effect on the seismic hazard at the construction site. On the other hand, the recent advances of earthquake engineering allow to include aftershocks in the hazard assessment through the so-called sequence-based PSHA (SPSHA). SPSHA modifies the formulation of PSHA and models aftershocks occurrence relying on the modified Omori law. For the United Kingdom (UK), the Omori parameters were recently estimated using a relatively simple procedure, and data from only four sequences. This study investigates the implications, on SPSHA results, of the Omori parameters, considering uniform hazard spectra (UHS) for three sites across the country, characterized by different seismic hazard according to PSHA. It found that, in the UK, the sensitivity of the UHS’ to the parameters choice is limited, whatever the seismic hazard of the site and the exceedance return period, likely because of the generally limited seismic hazard in the country.
2022
A sensitivity analysis of sequence-based seismic hazard assessment for the United Kingdom / Orlacchio, M.; Cito, P.; Iervolino, I.. - (2022). (Intervento presentato al convegno 3rd European Conference on Earthquake Engineering & Seismology tenutosi a Bucharest (Romania) nel 4-9 September 2024).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/988441
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