Multicriteria seismic risk assessment in Puerto Vallarta metropolitan area, Mexico

Abstract

The destructive effects of an earthquake are enhanced when the population is not prepared. The experiences from the past highlighted the importance of proper planning based on adequate scientific data. The Puerto Vallarta metropolitan area (PVMA) comprises medium-sized, rapid-growing urban areas of independent administrative and political entities that maintain a constant, direct socioeconomic interrelation. The PVMA is located in a region with a complex tectonic setting that produces important seismic activity and is affected by beaches, rivers, and estuary systems that produce complex soils and subsoil conditions. Moreover, the PVMA constantly undergoes anthropogenic processes that modify the local geomorphology and produce improper urbanization. Therefore, the PVMA constitutes an ideal natural laboratory to implement and test techniques to estimate seismic hazard, social vulnerability, and seismic risk. These techniques can be later implemented in other similar cities around the world. To determine the seismic hazard, social vulnerability, and seismic risk of the PVMA, we implemented the Multicriteria Evaluation Method within a Graphical Information System considering geomorphological (i.e., bedrock, soil, slope, curvature, flow accumulation), geophysical (peak ground acceleration, shear velocity, vibration frequency), and social information (population density, age, disabilities, health access, housing, and economic activity). We estimate the seismic hazard, social vulnerability, and seismic risk by considering three possible earthquakes. The results indicate a heterogeneous distribution of seismic risk with levels between moderate to high. Finally, a seismic risk microzonation in terms of the percentages of the seismic risk levels is proposed for the Puerto Vallarta metropolitan area.