Short-Term Interaction between Silent and Devastating Earthquakes in Mexico

Abstract

Triggering of large earthquakes on a fault that hosts aseismic slip or, conversely, triggering of slow slip events (SSE) by passing seismic waves involves seismological questions with major 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 quasistatic and/or dynamic perturbations. Such interaction seems to be conditioned by the transient memory of Earth materials subject to the "traumatic" stressing produced by the seismic waves of the great Mw8.2 Tehuantepec earthquake, which strongly disturbed the aseismic beating 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.

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.…”

3D modeling of long-term slow slip events along the flat slab segment in the Guerrero Seismic Gap, Mexico

“…The effect of the USL is incorporated in our model by the high pore fluid pressure assigned on the fault between 20-45 km. In central Mexico, the relatively shallow dipping angle (e.g., ∼12 between 20-45 km in Figure S8) of the Cocos plate compared with the neighbouring region may facilitate active dehydration reactions along a wider portion atop the slab (Manea & Manea, 2011), and thus promote long-term slow slip occurrence and low-frequency earthquakes (LFEs) accompanied with short-term SSEs on the downdip portion (Frank et al, 2015b).No obvious SSEs have been reported in the more flat southeastern segment of GSG based on current geodetic network (Radiguet et al, 2012;Cruz-Atienza et al, 2020). The absence of SSEs may be attributed to the less coupled fault interface from geodetic inversion (Radiguet et al, 2016) and the lack of USL from seismic imaging (Song et al, 2009;Dougherty & Clayton, 2014).…”

“…Recent time-dependent GPS modeling of the 2019 M w 7.0 SSE resolved aseismic slip in the northwestern GSG (Cruz-Atienza et al, 2020), implying that this region may host slow slip.…”