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

Abstract

The Guerrero seismic gap is presumed to be a major source of seismic and tsunami hazard along the Mexican subduction zone. Until recently, there were limited observations to describe the shallow portion of the plate interface in Guerrero. For this reason, we deployed offshore instrumentation to gain new seismic data and identify the extent of the seismogenic zone inside the Guerrero gap. We discovered episodic shallow tremors and potential slow slip events which, together with repeating earthquakes, seismicity, residual gravity and residual bathymetry suggest that a portion of the shallow plate interface in the Guerrero seismic gap undergoes stable slip. This mechanical condition may not only explain the long return period of large earthquakes with origins inside the Guerrero seismic gap, but also reveal why the rupture from past M<8 earthquakes on adjacent megathrust fault segments did not propagate into the gap to encompass a larger slip area. Nevertheless, a large enough earthquake initiating nearby could rupture through the entire Guerrero seismic gap if driven by dynamic rupture effects.

Along‐Dip Segmentation of the Slip Behavior and Rheology of the Copiapó Ridge Subducted in North‐Central Chile

“…(2019) recognized NVTs activity in the southern segment of the Japan subduction zone associated to the subduction of seamounts. NVTs activity is mainly located updip of SSE and a little in zone A, similar to what has been observed recently in the Mexico subduction zone (Plata‐Martinez et al., 2021). Moreover, NVTs activity is spatially correlated with CoR subduction (Figure 2a).…”

“…Plata‐Martinez et al. (2021) related the distribution of slow earthquakes in the Mexico subduction zone to the difference in relief produced by the subduction of seamounts. Therefore, we propose that the geometric heterogeneities of the seamounts of CoR could influence the diverse seismic behaviors observed in this zone.…”

Uncertainty quantification for fault slip inversion

“…It is consistent with the most recent inversions, where the region of maximum slip is located from 30 to 40 km depth and with a slight updip penetration in the north-west section [22,5]. Recent offshore observations showed that the mechanical properties in that segment of the subduction slab are different and it may explain the inferred updip slip [31]. Despite the similarities, it is important to mention that most of previous works are supported on constrained optimization framework and their solutions corresponds to the MAP, a different point-wise estimate than the one presented here (e.g., [4]; [5]).…”

CMT inversion for small-to-moderate earthquakes applying to dense short-period OBS array at off Ibaraki region

“…Tectonic tremors are slow earthquakes that are observed in the high-frequency (2-8 Hz) range (summarized in Obara & Kato, 2016). These separations of interplate regular and slow earthquakes have also been reported in various subduction zones (e.g., Dixon et al, 2014;Takemura et al, 2020;Plata-Martínez et al, 2021). Slow earthquakes tend to be concentrated in the regions with weak locking strengths (e.g., Takemura et al, 2019).…”