Short-term interaction between silent and devastating earthquakes in Mexico

Abstract

Either the triggering of large earthquakes on a fault hosting aseismic slip or the triggering of slow slip events (SSE) by passing seismic waves involve seismological questions with important hazard implications. Just a few observations plausibly suggest that such interactions actually happen in nature. In this study we show that three recent devastating earthquakes in Mexico are likely related to SSEs, describing a cascade of events interacting with each other on a regional scale via quasi-static and/or dynamic perturbations across the states of Guerrero and Oaxaca. Such interaction seems to be conditioned by the transient memory of Earth materials subject to the “traumatic” stress produced by seismic waves of the great 2017 (Mw8.2) Tehuantepec earthquake, which strongly disturbed the SSE cycles over a 650 km long segment of the subduction plate interface. Our results imply that seismic hazard in large populated areas is a short-term evolving function of seismotectonic processes that are often observable.

Shallow slow earthquakes to decipher future catastrophic earthquakes in the Guerrero seismic gap

“…Secondly, it could basically be unlocked and sliding freely with low coupling, thus decreasing the possibility of a large earthquake in the GG. Considering that onshore geodetic data suggest a lack of coupling along the NW-GG 14 , 15 , together with the inference of aseismic slip from STs and repeaters, it is reasonable to think that the offshore portion of the NW-GG (i.e., the silent zone) better corresponds to the second hypothesis of an almost freely sliding domain. The heterogeneous distribution of STs, repeaters, earthquakes and large variation of RG&BA, however, suggest local changes of mechanical properties at the offshore plate interface that cannot be explained with a simple unlocked model.…”

“…4 ). At farther distances, in Region C, only long-term SSEs and deep tremors occur 13 , 15 , 20 , 21 . Region C has similar slip behaviour as Region A, their difference should be in the mechanisms giving rise to slow earthquakes, with possibly subducted relief, increased pore pressure, sediments and a complex system of fractures facilitating slow earthquakes in Region A 43 .…”

“…The Guerrero subduction zone is also prone to slow earthquakes, including some of the largest slow slip events (SSE) in the world, with M w > 7.5, that repeat almost every 4 years 8 , 13 . Accordingly, the NW-GG accommodates stress aseismically as revealed by geodetic data, suggesting that coupling at the plate interface is approximately 75% lower than that of the bordering segments 14 , 15 . Since these contributions come from onshore observations, our knowledge of the shallow plate interface regions is limited.…”

Interplate Slip Rate Variation Between Closely Spaced Earthquakes in Southern Mexico: The 2012 Ometepec and 2018 Pinotepa Nacional Thrust Events

“…We included in this plot the 2017 M w 7.1 Puebla earthquake (Melgar, Ruiz-Angulo, et al, 2018;Singh et al, 2018), given their magnitude and societal impact. However, this event ruptured ∼250 km from the trench in the bending section of the slab and no static or dynamic transfer of stress has been found (Cruz-Atienza et al, 2021;Segou & Parsons, 2018). Cumulative RE counts show that the Ometepec-Pinotepa Nacional segment almost doubled the activity observed in the GG during the study period (2012-2021; Figure 5b).…”

3D Modeling of Long‐Term Slow Slip Events Along the Flat‐Slab Segment in the Guerrero Seismic Gap, Mexico

“…In contrast, no SSEs have been observed in this region (∼101.5-103.5 W) between 2001 and 2014 (Maury et al, 2018). Recent time-dependent GPS modeling of the 2019 M w 7.0 SSE resolved aseismic slip starting northwest of the GSG (Cruz-Atienza et al, 2021), implying that this region may host slow slip.…”