Multicriteria seismic hazard assessment in Puerto Vallarta metropolitan area, Mexico

Puerto Vallarta, a medium-size tourist city, located in the Pacific Coast of Mexico, in a similar way as many other coastal cities, combines human activity with the potential occurrence of natural hazard events. In this way, the use of new tools to evaluate the impact of such events seems imperative. Puerto Vallarta is located within a tectonic setting where the Rivera microplate subducts beneath the North American plate and is affected by seismic activity. We performed a seismic hazard assessment by implementing a GIS-based multicriteria evaluation model. The seismic microzonation map of Puerto Vallarta was performed using a criteria set of six thematic layers, i.e., peak ground acceleration values, soil, bedrock, slope gradient, curvature, and flow accumulation. We performed the integration of the criteria set by implementing the Analytical Hierarchy Process to assign a weight to each criterion according to its contribution to the seismic hazard, i.e., PGA (0.38), soil (0.25), rock (0.14), curvature (0.10), slope (0.08), and flow accumulation (0.07). The thematic maps were integrated using GIS according to the normalized weights. We classified the seismic hazard microzonation of Puerto Vallarta into five hazard levels, i.e., low (18%), low-medium (28%), medium (22%), medium–high (20%), and high (12%). The map shows heterogeneous distribution over the territory. However, the study area can be divided into three zones, i.e., the northern mountainous area, the Ameca River Valley, and the southern mountainous area. There is an overall increment of seismic hazard from south to north. However, the highest seismic hazard levels dominate the Rio Ameca Valley showing that it is more susceptible to deposits of soft sediment and thus can be affected in the occurrence of a major earthquake. The main objective of this paper was to implement a technique to quickly estimating seismic hazards levels using available data when there is no sophisticated geophysical and engineering analysis. Using the GIS-based multicriteria techniques in seismic hazard assessment allows to elucidated areas where factors influencing surface response to earthquakes interact and raise the soil amplification susceptibility.