Do slow slip earthquakes inhibit catastrophes? Geologic evidence from the Guerrero segment, Mexican subduction zone

Abstract

Globally, the largest tsunamigenic earthquakes have occurred along subduction zones. The Mw>9 devasting events in Chile, Sumatra, and Japan struck in areas where no instrumental records reported similar events. The one-thousand kilometer-long Mexican subduction zone (MSZ), where the Rivera-Cocos plates subduct under the North American plate, has no records of events of such magnitude. Historical and geologic evidence suggests the occurrence of a Mw8.6 tsunamigenic earthquake in the MSZ. However, the Guerrero segment (GS) has not experienced a large event in over 100 years. Several hypotheses have been proposed to explain this, e.g., slow slip events (SSEs) and the rheology of this segment favoring slow slip over rapid slip. However, none of these hypotheses have been confirmed with evidence. Here, we show geologic evidence that reveals a ca. 2000-year history of large tsunamigenic earthquakes and demonstrate that a Mw>8 event occurred ca. AD 1300 in this segment of the MSZ, indicating a long and variable earthquake recurrence (> 700 years). This evidence prompts the assessment of earthquake and tsunami potential using long-term evidence combined with instrumental observations along the MSZ and other subduction zones.