The 2017 México Tsunami Record, Numerical Modeling and Threat Assessment in Costa Rica

Abstract

An Mw 8.2 earthquake and tsunami occurred off- shore the Pacific coast of Me´xico on 2017-09-08, at 04:49 UTC. Costa Rican tide gauges have registered a total of 21 local, regional and far-field tsunamis. The Quepos gauge registered 12 tsunamis between 1960 and 2014 before it was relocated inside a harbor by late 2014, where it registered two more tsunamis. This paper analyzes the 2017 Me´xico tsunami as recorded by the Quepos gauge. It took 2 h for the tsunami to arrive to Quepos, with a first peak height of 9.35 cm and a maximum amplitude of 18.8 cm occurring about 6 h later. As a decision support tool, this tsunami was modeled for Quepos in real time using ComMIT (Community Model Interface for Tsunami) with the finer grid having a resolu- tion of 1 arcsec (* 30 m). However, the model did not replicate the tsunami record well, probably due to the lack of a finer and more accurate bathymetry. In 2014, the National Tsunami Moni- toring System of Costa Rica (SINAMOT) was created, acting as a national tsunami warning center. The occurrence of the 2017 Me´xico tsunami raised concerns about warning dissemination mechanisms for most coastal communities in Costa Rica, due to its short travel time.