Probabilistic Tsunami Hazard Analysis of the Pacific Coast of Mexico: Case Study Based on the 1995 Colima Earthquake Tsunami

Nobuhito Mori,Ario Muhammad,Katsuichiro Goda,Angel Ruiz-Angulo,Tomohiro Yasuda

doi:10.3389/fbuil.2017.00034

Abstract

This study develops a novel computational framework to carry out probabilistic tsunami hazard assessment for the Pacific coast of Mexico. The new approach enables the consideration of stochastic tsunami source scenarios having variable fault geometry and heterogeneous slip that are constrained by an extensive database of rupture models for historical earthquakes around the world. The assessment focuses upon the 1995 Jalisco-Colima Earthquake Tsunami from a retrospective viewpoint. Numerous source scenarios of large subduction earthquakes are generated to assess the sensitivity and variability of tsunami inundation characteristics of the target region. Analyses of nine slip models along the Mexican Pacific coast are performed and statistical characteristics of slips (e.g. coherent structures of slip spectra) are estimated. The source variability allows exploring a wide range of tsunami scenarios for a moment magnitude (Mw) 8 subduction earthquake in the Mexican Pacific region to conduct thorough sensitivity analyses and to quantify the tsunami height variability. The numerical results indicate a strong sensitivity of maximum tsunami height to major slip locations in the source, and indicate major uncertainty at the first peak of tsunami waves.

Highlights

An accurate assessment of tsunami hazards and quantification of uncertainty associated with the assessment are essential to mitigate and to control disaster risk exposures from a tsunami risk management point of view
A brief discussion of generated synthetic/stochastic tsunami sources for the Guerrero region is given before analyzing synthetic tsunami characteristics
Our aim in setting up the case study is to compare the results of stochastic tsunami simulations with the past survey data of the 1995 Colima Earthquake

Summary

INTRODUCTION

An accurate assessment of tsunami hazards and quantification of uncertainty associated with the assessment are essential to mitigate and to control disaster risk exposures from a tsunami risk management point of view. The earliest study that con sidered the probabilistic nature of tsunami hazard was by Rikitake and Aida (1988) They did not consider a full PTHA methodology, they used historical records and a typical earthquake fault model to estimate the probability of tsunami height exceeding a certain level at the shoreline. The recent geophysical investigations by Perez-Campos et al (2008) and Pacheco and Singh (2010) indicate that the Cocos Plate is subducting beneath the North American Plate with a dip angle of about 15°, and the slab reaches a depth of about 25 km at the distance of about 65 km from the Trench In this region, both interface events and inslab events may be generated. This study develops a stochastic source model for large tsunamigenic earthquakes in the Guerrero region. New scaling relationships of various earthquake source parameters, such as fault geometry and slip statistics, have been developed for tsunamigenic events (Goda et al, 2016). Mw W (km) L (km) Strike (°) Dip (°) Mean Maximum Box–Cox Correlation length Correlation Hurst Reference slip (m) slip (m) parameter along dip (km) length along number strike (km)

5: Colima

9: Oaxaca

RESULTS AND DISCUSSION

CONCLUSION