GUTENBERG-RICHTER B VALUE STUDIES ALONG THE MEXICAN SUBDUCTION ZONE AND DATA CONSTRAINTS

Abstract

The Gutenberg-Richter b value is one of the most important tools for seismic hazard studies; this value is most useful in estimating seismicity rates, and also is related to ambient stress levels and shows changes precursory to the occurrence of large earthquakes. However, correct and reliable determinations of the b value are critically dependent on having enough data samples. Studies oriented to corroborate whether precursory changes in the b value occur before large (M ≥ 7.0) along the Mexican subduction zone, were done based on data from the Servicio Sismológico Nacional (SSN, Mexico’s National Seismological Service) seismic catalog, from 1988 to 2018. Results for five earthquakes are suggestive that precursory changes may occur, but differences between measured values are not statistically significant because of large uncertainties due to the SSN using different magnitude scales for small (below M ~4.5) and medium to large (above M ~4.5) magnitudes. We discuss some limitations about the applicability of SSN data.