A Test of the Earthquake Gap Hypothesis in Mexico: The Case of the Guerrero Gap
The seismic gap hypothesis has been widely cited in Mexico to predict the location of future earthquakes. However, no analysis of the outcome of any predictions of the hypothesis in Mexico has been done to date. This work analyzes the outcome of the prediction by Nishenko and Singh (1987a), which is based on probability distribution functions over time in defined segments that allow for a formal evaluation. Specific probabilities were given for 5, 10, and 20 yr after 1986, using the cumulative distribution function. The prediction relies on the precise repeat times of characteristic earthquakes to define the segments, but we show that the catalog the authors use relies on an imprecise definition of characteristic earthquakes. We discuss some of their decisions in building their catalog to explain how we analyze the outcome of the prediction. An unexpected result is that the very catalog the authors use to create the gap hypothesis prediction does not seem to support a narrow recurrence interval and instead seems to suggest large variability in earthquake recurrence intervals along the Mexican subduction zone. We generate null model earthquake catalogs using the average number of earthquakes that occur in the subduction zone and randomly distribute these along the segments according to their relative lengths. We find that the null model performs better than the seismic gap hypothesis prediction. No earthquakes occur in segments with a 70% or higher probability according to NS1987 (there were four such segments in the 20-year time frame), but an Mw 8.0 earthquake occurs in a segment with a less than 16% probability of an earthquake. We conclude that the gap hypothesis performed poorly at predicting earthquakes in Mexico and, in fact, its predictions were worse than predicting earthquakes by chance.
© 2023 Seismological Society of America. Maximillan J. Werner and Jose A. Bayona have received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement Number 821115, Real‐time earthquake rIsk reduction for a reSilient Europe (RISE), available at http://www.rise-eu.org, last accessed October 2022). DATA AND RESOURCES. All data used in this article came from the published sources listed in the references. The authors acknowledge that there are no conflicts of interest recorded.