A Probabilistic Tsunami Hazard Model for Disaster Resilience Assessment of Puerto Rico

Probabilistic methods in tsunami hazard assessment studies are becoming more common, replacing deterministic "design scenario" approaches, since they cover a broader range of plausible scenarios while addressing the uncertainties associated with them. In this presentation we will take a step forward and not only provide the probabilistic tsunami hazard maps produced for Puerto Rico but also demonstrate likelihoods of risk posed by tsunamis on the built environment for different construction (reinforced concrete, wood frame, unreinforced masonry etc.) and occupancy (residential, industrial etc.) classes as well as the age of structures.

The results are based on our probabilistic tsunami hazard model developed for the Caribbean. This model consists of ~6000 earthquakes derived from a 100,000 year-long, time-dependent, stochastic earthquake catalog developed as part of regional probabilistic seismic hazard analysis. In our model, we generate single and multi-segment fault rupture scenarios with random slip distributions, utilizing high-resolution (90 meters or better) bathymetry data and Manning's roughness coefficient maps derived from high-resolution land-use/land-cover datasets. Tsunami model outputs are then integrated with the vulnerability component of AIR earthquake model to translate hazard into expected damage and monetary losses. These vulnerability functions are derived analytically for each class of building through a hybrid approach that combines engineering analysis and available observational data for different construction types, height, and age.

We first present annual exceedance probabilities of flow speeds and wave amplitudes near major cities of Puerto Rico as well as their spatial distributions for several return periods (475, 1000, 2475 and 10000 years). Then we demonstrate the estimated mean damage and probability of failure for structures based on the construction classes and their distances from the coastline. The primary benefit of this effort would be to improve the resiliency of coastal communities to tsunami hazard and associated risks, where the risk is defined as the probability of the event times the consequence.