TSUNAMI DEPOSITS REVEAL POTENTIAL FOR HIGH-MAGNITUDE EARTHQUAKES IN THE GUERRERO SEISMIC GAP, MEXICO
The world’s most powerful tsunamigenic earthquakes have occurred along subduction zones. Catastrophic events exceeding magnitude 9, such as those in Chile, Sumatra, and Japan, have struck areas with no prior instrumental records of such earthquakes. Although no similar events have been recorded along the 1,000 km-long Mexican subduction zone, historical accounts and geological data suggest that a magnitude 8.6 tsunamigenic earthquake may have occurred in the past. Notably, the Guerrero seismic gap has not experienced a large-magnitude earthquake in over a century.
In this study, we present multidisciplinary evidence from the Guerrero coast based on analyses of sediment grain size, geochemistry, microfossils, magnetic properties, and radiometric and optically stimulated luminescence dating. These data document a 2,000-year record of significant tsunamis likely triggered by major seismic events. Numerical modeling supports the occurrence of a magnitude >8 earthquake around the year 1300 within the Guerrero seismic gap. These findings highlight the importance of integrating long-term geological records with instrumental data to better assess earthquake and tsunami hazards along subduction zones worldwide.