A geologic recipe for transient slip within the seismogenic zone: Insight from the Guerrero seismic gap, Mexico

Husker, Allen; Ferrari, Luca; Arango-Galván, Claudia; Corbo-Camargo, Fernando; Arzate-Flores, Jorge

doi:10.1130/g39202.1

Cited by 17 publications

(14 citation statements)

References 21 publications

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“…This hypothesis is also supported by Husker et al. (2018), who found a gabbroic lower crust that acts as a seal, trapping the fluids from the subduction zone within the slab.…”

Section: Discussionsupporting

confidence: 63%

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Crustal and Upper‐Mantle Structure Below Central and Southern Mexico

Peter

Ortíz-Alemán

2021

JGR Solid Earth

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Along the Middle American Trench (MAT), the Cocos Plate subducts beneath the North American Plate producing large seismic events, slow slip events (SSE), tectonic tremors (TT) and an unusual orientation of the Trans-Mexican Volcanic Belt (TMVB) (Manea et al., 2013; Figure 1). The subducting Cocos slab is complex due to the variability in age, the convergence rate and dip angle along the MAT. Pardo and Suárez (1995) first described the unusual sub-horizontal subduction beneath Central Mexico based on relocated hypocenters of local and regional earthquakes. They were unable to determine the geometry of the slab beneath the TMVB, however, due to the scarce seismicity in this region.To improve understanding of the subduction of the Cocos plate under the North American Plate, new temporal seismic networks were deployed in Mexico. As a result, new crust and upper mantle models were obtained by different seismological methodologies. In Central Mexico, teleseismic converted phases studies

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“…This hypothesis is also supported by Husker et al. (2018), who found a gabbroic lower crust that acts as a seal, trapping the fluids from the subduction zone within the slab.…”

Section: Discussionsupporting

confidence: 63%

“…An alternative interpretation is that the fluids that are associated with the USL are trapped in the interface. This hypothesis is also supported by Husker et al (2018), who found a gabbroic lower crust that acts as a seal, trapping the fluids from the subduction zone within the slab.…”

Section: Lateral Slow-velocity Featuresmentioning

confidence: 56%

Crustal and Upper‐Mantle Structure Below Central and Southern Mexico

Peter

Ortíz-Alemán

2021

JGR Solid Earth

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“…All of our observations indicate that the central portion of the NW-GG is dominated by a weakly coupled domain. Weak coupling, offshore and onshore, explains the long recurrence period of large earthquakes in the GG 45 . This implies that the initiation of a M > 8 earthquake in the NW-GG is less likely to occur as previously expected; however, the risk of a rupture of the GG does not disappear.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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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 at the shallow portion of the plate interface offshore Guerrero, so we deployed instruments there to better characterize the extent of the seismogenic zone. Here we report the discovery of episodic shallow tremors and potential slow slip events in Guerrero offshore. Their distribution, together with that of repeating earthquakes, seismicity, residual gravity and bathymetry, suggest that a portion of the shallow plate interface in the gap undergoes stable slip. This mechanical condition may not only explain the long return period of large earthquakes inside the gap, but also reveals why the rupture from past M < 8 earthquakes on adjacent megathrust segments did not propagate into the gap to result in much larger events. However, dynamic rupture effects could drive one of these nearby earthquakes to break through the entire Guerrero seismic gap.

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“…Drainage would in turn control the downdip extent of the seismogenic zone of the megathrust. The drier conditions of the subducting interface trenchward would promote fast seismogenic rupture while downdip the strike slip faults, fluid saturation would result in slow slip events within the transition zone (Husker et al, 2018). This cloud directly influence the seismic hazard of Puerto Rico in case of a megathrust earthquake on the Muertos subduction.…”

Section: Discussionmentioning

confidence: 99%

The 2019-2020 Indios, Puerto Rico earthquake sequence: seismicity and faulting

Vičič¹,

Momeni²,

Borghi³

et al. 2021

Preprint

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The 2019-2020 Indios, Puerto Rico earthquake sequence ruptured on multiple faults with several moderate magnitude earthquakes. Here we investigate the seismotectonics of this fault system using high precision hypocenter relocation and inversion of the near-field strong motions of five largest events in the sequence (5.6≤Mw≤6.4) for kinematic rupture models. The Mw6.4 mainshock occurred on an NE striking, SE dipping normal fault. The rupture nucleated offshore ~15 km SE of Indios at the depth of 8.6 km and extended SW-NE and updip with an average speed of 1.55 km/s, reaching the seafloor and shoreline after about 8 seconds. The Mw5.7 and Mw5.8 events on 6 th and 7 th January 2020, respectively, occurred on two E-SE striking, near-vertical, left-lateral strike-slip faults. However, the 7 th January 2020 Mw5.8 aftershock which occurred only 10 minutes after the mainshock, ruptured on a fault with almost the same strike as the mainshock but situated ~8 km further E, forming a set of parallel faults in the fault system. On 11 th January 2020, a Mw6.0 earthquake occurred on a N-NE striking, W dipping fault, orthogonal to the faults hosting the strike-slip earthquakes. We also apply template matching for the detection of missed, small magnitude earthquakes and to study the spatial evolution of the main part of the sequence. These detections show multiple examples of acceleration phases before moderate earthquakes and reveal migration patterns within the sequence. Using the template matching results along with GPS analysis, we image the temporal evolution of a foreshock sequence (Caja swarm). We propose that the swarm and the main sequence were a response to an inferred tectonic transient that most likely originated on the Muertos subduction as a slow-slip event.rupturing events, around 5.000 years ago (Prentice and Mann, 2005), while the Salinas fault ruptured twice in the past 10.400 years (Piety et al., 2018). We study the geometry (Fig. 1) of the faults activated in the SW of Puerto Rico during the 2019-2020 Indios sequence by relocating the sequence and performing the kinematic sourcerupture modelling of the five largest events (5.6

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A geologic recipe for transient slip within the seismogenic zone: Insight from the Guerrero seismic gap, Mexico

Cited by 17 publications

References 21 publications

Crustal and Upper‐Mantle Structure Below Central and Southern Mexico

Crustal and Upper‐Mantle Structure Below Central and Southern Mexico

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

The 2019-2020 Indios, Puerto Rico earthquake sequence: seismicity and faulting

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