Seismic Hazard Analysis at Los Mochis, Sinaloa, Mexico

Abstract

We studied the regional seismic hazard of the state of Sinaloa with emphasis on Los Mochis city, located in the municipality of Ahome, Sinaloa. Acceleration in rock was determined for different return periods (Tr = 475, 975, and 2475 years). We compared these results with the spectral accelerations proposed in the buildings seismic design Handbook by Earthquake of the Federal Electricity Commission (commonly applied in Mexico when absence of local regulations). It was observed that the seismic hazard was very sensitive to changes in the geometry of the source that contributes most to seismic hazard of the city. Particularly, PGA values were compared for 475 years, and it was observed that the increase in the PGA value due to that adjustment was approximately 35%. Additionally we performed a zonation study in the city, based on microtremors using single-station by applying horizontal-to-vertical spectral ratios (HVSR) analysis to 32 sites within the city. Results show low variations with higher values of natural period of resonance (To) in the southwest of the city. We explore a possible response for the entire valley by calculating a seismic hazard curve in terms of amplification factors.