Who Needs ETAS-based Seismic Hazard?
Description:
Earthquakes typically occur in space-time clusters, each identifying a seismic sequence. Nevertheless, because of catalog de-clustering/completeness and calibration easiness, classical probabilistic seismic hazard analysis (PSHA) only accounts for the largest magnitude event within the sequence, which is recognized as the mainshock. PSHA models the mainshock occurrence over time according to a homogeneous Poisson process (HPP), which is defined by its time-invariant rate, while it neglects foreshocks and aftershocks, that is, those events within the sequence preceding and following the mainshock, respectively. This means that seismic hazard is underestimated, and that risk assessment cannot contemplate structural failure due to non-mainshock events or damage accumulation within each sequence. Because of some recent advances in PSHA, it is now possible to include aftershocks in the long-term seismic hazard assessment through sequence-based PSHA (SPSHA), which still has the advantages of using de-clustered catalogs. SPSHA assumes that the mainshocks-aftershocks sequences occur following the HPP adopted for mainshocks, whereas the occurrence of aftershocks, within each sequence, is described via a non-homogeneous Poisson process, whose rate decreases with the time elapsed from the mainshock according to the modified Omori law. A – trendy and computationally more demanding – alternative for modelling seismic clusters, is represented by the epidemic-type aftershock sequences (ETAS) models. In the ETAS framework, starting from a background HPP, each event within the sequence may generate its own Omori-type sequence. In the presented study, the close links between SPSHA and ETAS-based hazard are discussed. Furthermore, a comparison between ETAS and SPSHA, in terms of seismic hazard and structural risk assessment – with and without seismic damage accumulation – is addressed, considering two sites in Italy exposed to high and low hazard and state-of-the art structural models. The final goal is to determine whether ETAS models are necessity for earthquake engineering applications or more a research trend in seismology.
Session: Advancing Time-dependent PSHA and Seismic Risk Assessment: Accounting for Short- to Medium-term Clustering - I
Type: Oral
Date: 4/15/2025
Presentation Time: 10:45 AM (local time)
Presenting Author: Iunio
Student Presenter: No
Invited Presentation: Yes
Poster Number:
Authors
Iunio Iervolino Presenting Author Corresponding Author iunio.iervolino@unina.it University of Naples Federico II, IUSS – Scuola Universitaria Superiore di Pavia |
Pasquale Cito pasquale.cito@unina.it University of Naples Federico II |
Eugenio Chioccarelli eugenio.chioccarelli@unirc.it Mediterranea University of Reggio Calabria |
Antonio Vitale antonio.vitale5@unina.it University of Naples Federico II |
Massimiliano Giorgio massimiliano.giorgio@unina.it University of Naples Federico II |
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Who Needs ETAS-based Seismic Hazard?
Session
Advancing Time-dependent PSHA and Seismic Risk Assessment: Accounting for Short- to Medium-term Clustering