Probabilistic Seismic Hazard Estimates for Zacatecas, Central Mexico

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

Four regional uniform-area crustal seismic source zones are used in a probabilistic seismic hazard analysis for the Zacatecas region of Central Mexico. The preferred, lower and upper bound earthquake recurrence parameters (a- and b-values) in the four seismic source zones are based on the short (~10 years) instrumental earthquake record from Zúñiga et al. (2017), the tectonic development in the surrounding physiographic regions of Mexico, and comparison to analogous regions of North America that have more robust earthquake recurrence parameters. Hazard curves confirm the relatively low seismic hazard, with 5%-damped, mean PGA values of 0.05 g, 0.14 g and 0.28 g for 475-year, 2,475-year and 10,000-year return periods, respectively. Hazard deaggregation analysis indicates that the PGA to 0.2 s spectral accelerations at a 475-year return period arise from moderate-magnitude earthquakes (i.e., M_W5.0 to M_W6.0) at distances of about 50 km. Larger magnitude earthquakes (M_W6.5+) at distances greater than 135 km dominate the 475-year return period hazard at periods longer than about 1.0 s. At the 10,000-year return period the mean PGA of 0.27 g has a dominant hazard contribution from larger (M_W ≥7) far-field earthquakes. Estimated earthquake ground motions are sensitive principally to the uncertainties related to the a- and b-value recurrence parameters and the ground motion model selection and weighting. The relative tectonic quiescence and the incomplete earthquake records in the region impede the evaluation of robust recurrence parameters, and hence, increase the level of uncertainty in the seismic hazard.

Presenting Author: Alan G. Hull

Authors