An improvement of tsunami hazard analysis in Central Chile based on stochastic rupture scenarios

ABSTRACT

Central Chile is exposed to tsunami hazard, and large earthquakes and tsunamis have occurred over the last 500 years. Tsunami hazard analysis in Chile has been traditionally implemented by means of a deterministic approach, which is based on historical events and uniform slip distribution. The objective of the present study is to improve tsunami hazard analysis in central Chile (30°S to 38°S). To encompass the purpose, stochastic earthquake scenarios of magnitude $M_w$ 8.8 to 9.2 were generated. Two different sets of stochastic tsunami scenarios were selected by means of the Stochastic Reduced Order Model (SROM), which were applied to Quintero bay to perform a Probabilistic Tsunami Hazard Analysis (PTHA). The results showed that PTHA of Quintero bay from stochastic tsunami scenarios agrees with paleotsunami records in the bay, while a deterministic tsunami scenario underestimated the hazard. Two sets (50 and 100 scenarios, respectively) give similar results when smaller return periods are analyzed. However, for larger return periods ($>$2000 yr) the set of 100 scenarios show better results consistent with previous paleoseismological findings. The methodology implemented here can be replicated in other seismic regions in Chile as well as in other active subduction zones, thus, both near field and far field events can be analyzed.

KEYWORDS:

• Tsunami
• central Chile
• probabilistic tsunami hazard analysis
• stochastic rupture scenarios

Acknowledgments

The authors would like to thank the Centro de Investigación para la Gestión Integrada del Riesgo de Desastres (CIGIDEN), ANID/FONDAP/15110017, as well as the post doctoral projects ANID/FONDECYT/3190322 and 3200772. This research was partially supported by the supercomputing infrastructure of the NLHPC (ECM-02). The authors also thank Dr. Ignacio Sepulveda for providing matlab scripts to analyze the Okada formulation and guidance on the application of SROM as well as Dr. Patricio Winckler for providing topography data of Quintero bay. RB acknowledges funding from ANID/PIA/ACT192169 and IB acknowledge the support from the Master programme at Universidad Catolica de la Santisima Concepcion. The authors would also like to acknowledge the time and effort taken by the two reviewers who provided constructive comments to enhance the quality of the manuscript. The stochastic tsunami scenarios are available at http://dx.doi.10.17632/zh7vf6pwfz.2.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the ANID/FONDAP [15110017]; ANID/PIA [ACT192169]; ANID/FONDECYT [3190322]; ANID/FONDECYT [3200772].