Times of increased probability of large earthquakes ( Ms ≥ 7.5) along the Mexican subduction zone

Abstract

Using the method of pattern recognition of infrequent events, we explore the possibility of identifying the times of increased probability (TIP) of occurrence of large earthquakes ( M s ≥ 7.5) along the Mexican subduction zone. A TIP refers to a 5 year period within which a strong earthquake has a high probability of occurrence. We analyzed the seismicity for the regions of Chiapas-Eastern Oaxaca (91–97°W, Region 1), Western Oaxaca-Guerrero (97–102°W, Region 2), and Michoacan-Colima-Jalisco (102–106°W, Region 3) for the time interval 1970–1991 with the National Oceanic and Atmospheric Administration seismic catalog as the source data. The premonitory intermediate-term seismic activation to identify a TIP was measured using the algorithm M8. Three out of the five earthquakes of M s ≥ 7.5 that occurred during the studied period are diagnosed by algorithm M8, and for the Region 3 segment a TIP is identified that will end between 1994 and 1996. We consider the area between the Western Colima gap and the Jalisco region (103.7–106.0°W) as the zone where the forecast earthquake has a higher than usual probability of occurrence. Our results by no means constitute a definitive earthquake prediction but suggest the need for detailed seismic analysis and the study of other geophysical precursors along the Colima-Jalisco segment.