<p>I present a time-independent new probabilistic seismic hazard analysis (PSHA) for El Salvador contrasting area sources and smooth seismicity methods regarding horizontal peak ground and spectral accelerations for 5% of critical damping at 0.2 and 1 s periods. Firstly, a new earthquake catalog is compiled regarding moment magnitude, covering historical and instrumental seismicity for 1528–2023. Secondly, I propose new features to characterize the upper-crustal volcanic chain source, namely, a multi-linear Gutenberg-Richter relationship and a constant bandwidth distance amongst epicenters. I use a three-dimensional geometry subduction zone in the analysis, considering the primary focal mechanism along the slab: thrust and normal faulting; the difference between reverse interface and reverse intraplate shocks is highlighted as a new component in the PSHA. Thirdly, in order to treat the epistemic uncertainty and justify the proper weighting in a logic tree, available ground motion prediction equations are tested with actual accelerometric data for moderate and destructive earthquakes in El Salvador. Finally, seismic hazard maps are derived compatible with the American Society of Civil Engineers (ASCE) standards for rock site conditions with a V<sub>S30</sub> of 760 m/s and flat topography setting 50, 95, 475, 975, and 2475 years of return period. Simultaneously, the results are contrasted with ground motion from fault-based PSHA employing preliminary geodetic data, the actual seismic loads prescribed in the regulations, and former research works. All sets of seismic hazard maps are presented in the electronic supplement of this article.</p>

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Probabilistic seismic hazard analysis for El Salvador

  • Walter Salazar

摘要

I present a time-independent new probabilistic seismic hazard analysis (PSHA) for El Salvador contrasting area sources and smooth seismicity methods regarding horizontal peak ground and spectral accelerations for 5% of critical damping at 0.2 and 1 s periods. Firstly, a new earthquake catalog is compiled regarding moment magnitude, covering historical and instrumental seismicity for 1528–2023. Secondly, I propose new features to characterize the upper-crustal volcanic chain source, namely, a multi-linear Gutenberg-Richter relationship and a constant bandwidth distance amongst epicenters. I use a three-dimensional geometry subduction zone in the analysis, considering the primary focal mechanism along the slab: thrust and normal faulting; the difference between reverse interface and reverse intraplate shocks is highlighted as a new component in the PSHA. Thirdly, in order to treat the epistemic uncertainty and justify the proper weighting in a logic tree, available ground motion prediction equations are tested with actual accelerometric data for moderate and destructive earthquakes in El Salvador. Finally, seismic hazard maps are derived compatible with the American Society of Civil Engineers (ASCE) standards for rock site conditions with a VS30 of 760 m/s and flat topography setting 50, 95, 475, 975, and 2475 years of return period. Simultaneously, the results are contrasted with ground motion from fault-based PSHA employing preliminary geodetic data, the actual seismic loads prescribed in the regulations, and former research works. All sets of seismic hazard maps are presented in the electronic supplement of this article.