Probabilistic tsunami hazard assessment and flood modeling: A case study of Manzanillo, Colima, Mexico

This study presents a probabilistic tsunami hazard assessment (PTHA) for Manzanillo, Colima, a coastal city in Mexico, which is vulnerable to local tsunamis due to its proximity to the subduction zone along the Mesoamerican Trench. Historical records show that the region experienced major tsunamis, notably in 1932 and 1995. Using stochastic earthquake source models and numerical simulations, we calculated the tsunami inundation scenarios for different return periods (50, 100, and 500 years). The study employed the GeoClaw open-source software package, incorporating high-resolution topography and bathymetry, to simulate tsunami wave propagation and coastal inundation. Model validation using the 1995 Colima-Jalisco event demonstrates that the simulation correctly captures the observed tsunami characteristics. The results revealed that lowland areas, particularly near Manzanillo and Santiago Bays, and the Cuyutlán Lagoon, could experience inundation of several kilometers inland in a worst-case scenario. Probability-of-exceedance curves indicate a high likelihood of moderate to significant tsunami wave heights within a 50-year time frame, underscoring the substantial risk to the city. These findings provide crucial information for local authorities to develop effective tsunami risk management strategies including hazard mapping, improved building codes, and emergency preparedness plans.