Deaggregation of probabilistic seismic hazard results for some selected cities in Western Mexico

Here we present a deaggregation appraisal conducted for 15 selected significant cities in Western Mexico, for four oscillation periods (PGA, SA (0.2 s), SA (1.0 s), and SA (2.0 s)), also considering a different input for the soil condition (for B, B/C and C NEHRP site classes), and for two return periods (475 and 975 years). This study is based on a previous complete recently published seismic hazard evaluation for the region. An area source model consisting of thirty-seven seismic sources has been used alternatively in a logic tree with a spatially smoothed seismicity model for the same region. The obtained hazard deaggregation results prove that for most of the studied cities -those located along the Pacific coast-, nearby seismic sources are contributing most to the seismic hazard at the studied location, especially for lower periods (PGA and SA (0.2 s)). However, for a few cities far from the Middle America Trench, distant large-magnitude earthquakes contribute more to the seismic hazard, especially at larger spectral periods (SA (1.0 s) and SA (2.0 s)). Additionally, this study shows that the differences in the soil conditions for the computed return periods, have a little influence on the obtained deaggregation results.

Automated summary

This study presents a deaggregation appraisal for 15 significant cities in Western Mexico, considering different oscillation periods, soil conditions, and return periods. The results show that nearby seismic sources contribute most to the seismic hazard for most cities, especially at lower periods. However, for cities far from the Middle America Trench, distant large-magnitude earthquakes contribute more to the seismic hazard, especially at larger spectral periods. Additionally, the study finds that soil conditions have little influence on the deaggregation results.