The earthquake of 16 November, 1925 (Ms=7.0) and the reported tsunami in Zihuatanejo, Mexico

Abstract

A feasibility study to develop a tsunami alert system for Mexican earthquakes, using broadband seismograms from the National Seismological Service, is currently under way. A first step in this direction is a revision of the Mexican tsunami catalogs. In these catalogs, one of the largest tsunamis of this century is reported in the Port of Zihuatanejo and has been re- lated to an earthquake which occurred on November 16, 1925. This earthquake was located at a distance of about 600 km from Zihuatanejo and had a surface-wave magnitude, Ms, of 7.0. In developing a tsunami alert system, it is important t o know if the tsunami was indeed related to the earthquake of 1925. In this note we examine available evidence and find thatthe tsunami was not related to the earthquake. There is no evidence of a local earthquake near Zihuatanejo which may have resulted in the tsunami. We conclude that the tsunami was either caused by slumping of the sea floor near Zihuatanejo or by a meteorological phenomenon in the region.