Interseismic coupling along the Mexican subduction zone seen by InSAR and GNSS

Maubant, Louise; Radiguet, Mathilde; Pathier, Erwan; Doin, Marie‐Pierre; Cotte, Nathalie; Kazachkina, Ekaterina; Kostoglodov, V.

doi:10.1016/j.epsl.2022.117534

Cited by 13 publications

(10 citation statements)

References 43 publications

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“…If we assume that plate coupling is purely a measure of temporal intermittence of slip (W. B. Frank, 2016), this implies that a partial coupling (≤1) directly tells just how often a given fault is slipping, being fully locked the rest of the time. While this is only one potential explanation of partial plate coupling, our results support the idea that estimates of plate coupling depend on the time scales over which they are calculated (W. B. Frank, 2016; Jolivet & Frank, 2020; Maubant et al., 2022). This bears out in our observations where we see that the instantaneous coupling at 6 hr is consistently higher than at 24 hr as shown in Figures 5c and 5d.…”

Section: Discussionsupporting

confidence: 82%

“…While this is only one potential explanation of partial plate coupling, our results support the idea that estimates of plate coupling depend on the time scales over which they are calculated (W. B. Frank, 2016;Jolivet & Frank, 2020;Maubant et al, 2022). This bears out in our observations where we see that the instantaneous coupling at 6 hr is consistently higher than at 24 hr as shown in Figures 5c and 5d.…”

Section: Slow Slip Is the Competition Between Subdaily Dynamics And A...supporting

confidence: 87%

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Subdaily Slow Fault Slip Dynamics Captured by Low‐Frequency Earthquakes

et al. 2023

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Geodetic positioning is the geophysical record of reference for slow slip events, but typical daily solutions limit studies of the evolution of slow slip to its long‐term dynamics. Accompanying seismic low‐frequency earthquakes located precisely in time and space provide an opportunity to image slow slip dynamics at subdaily time scales. Here we show that a high‐resolution time history of low‐frequency earthquake fault slip alone can reproduce the geodetic record of slow slip that we observe to be dominated by subdaily fault slip dynamics. However, a simple linear model cannot accommodate the complex dynamics present throughout the slow slip cycle, and an analysis of different phases of the slow slip cycle shows that the ratio of geodetic to seismic fault slip varies as a function of time. This suggests that the low‐frequency earthquake source region saturates as slow slip grows in moment and area. We propose that rheological heterogeneities at the plate boundary associated with low‐frequency earthquakes do not play a significant role in the slow slip rupture process, thus implying that their activity is incidental to the driving aseismic slip.

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Section: Discussionsupporting

confidence: 82%

Section: Slow Slip Is the Competition Between Subdaily Dynamics And A...supporting

confidence: 87%

Subdaily Slow Fault Slip Dynamics Captured by Low‐Frequency Earthquakes

et al. 2023

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“…Whether there is residual deeper slip left to be used in future events is not possible to ascertain at this point. Although geodetic coupling models suggest the potential for this -they image meaningful coupling at least to 25-30 km depths in this region (Rousset et al, 2016, Maubant et al, 2022 Whether the up-dip limit of slip for the event is reliable is important. It has been shown that, unlike in strictly static inversions, where offshore slip occurs is uniformly difficult to pin down, the use of time-varying data such as HR-GNSS and strong motion data greatly ameliorates this.…”

Section: Figure 5 Inversion Sensitivity Analysis Using a Jackknife Ap...mentioning

confidence: 99%

The Mechanisms of Tsunami Amplification and the Earthquake Source of the 2021 M7 Acapulco, Mexico, Earthquake

Melgar¹,

Ruiz‐Angulo²,

Crowell³

et al. 2022

Preprint

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Here we show a slip model for the 2021 M7 Acapulco, Mexico, earthquake produced by inversion of strong motion, GNSS, tide gauge, and InSAR data. The earthquake occurs within the Guerrero gap, identified as a region of concern for its seismogenic potential and paucity of large events. We find that rupture was compact, constrained to depths between 10 and 20 km and consistent of two main slip patches. The slip model leaves a broad swath of the megathrust unbroken. Whether the event signals a reactivation of large earthquakes in the region remains unknown. We find that tide gauge recordings inside Acapulco Bay for the M7 1962 earthquake and the 2021 event are strikingly similar, we interpret this as weak evidence that 2021 is a repeat of 1962. We also produce a high resolution hydrodynamic model of the resulting tsunami using the slip model as initial condition and place special emphasis in understanding the long duration (~17 hr) of waves inside the bay. We find that simple bay resonance alone does not account for the features of the event. Rather it is a complex interaction with shelf modes and edge waves which continuously re-excite the bay resonance that leads to the protracted tsunami disturbances. Furthermore, we find that significant currents in excess of 1 m/s occur in localized portions of the bay even when wave amplitudes remain small.

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“…Because of the distance of the trench from land, the resolution of fault motion is typically poor. Modern Synthetic Aperture Radar (SAR) constellations directly tackle this issue of spatial resolution by measuring ground displacement over hundreds of kilometers with repeat times <24 d through Interferometric Synthetic Aperture Radar (InSAR) analysis, whose spatial resolution is in the order of up to 10 m. With each pixel of the radar images acting as its own geodetic sensor, this allows for dense spatial coverage of the surface velocity field that complements GNSS (Maubant et al., 2022). The precision of InSAR ground displacement is much lower than that of GNSS, making it challenging to measure the surface displacement due to relatively small fault motions, such as a slow slip event (Maubant et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

“…The discovery of slow slip along subduction zones more than two decades ago (Dragert et al., 2001) has upended this simple conceptual model of a stationary (e.g., constant slip deficit rate) interseismic phase in these tectonic settings (e.g., Frank, 2016; Maubant et al., 2022; Mouchon et al., 2023; Saux et al., 2022). Geodetic observations across many tectonic plate boundaries have demonstrated how these transient slip events, which do not radiate seismic waves, can episodically release as much accumulated tectonic stress as major earthquakes (>M7) (e.g., Graham et al., 2016; Wallace, 2020).…”

Section: Introductionmentioning

confidence: 99%

Imaging the Spatiotemporal Evolution of Plate Coupling With Interferometric Radar (InSAR) in the Hikurangi Subduction Zone

Maubant,

Frank,

Wallace

et al. 2023

Geophysical Research Letters

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The coupling at the interface between tectonic plates is a key geophysical parameter to capture the frictional locking across plate boundaries and provides a means to estimate where tectonic strain is accumulating through time. Here, we use both interferometric radar (InSAR) and Global Navigation Satellite System (GNSS) data to investigate the plate coupling of the Hikurangi subduction zone beneath the North Island of New Zealand, where multiple slow slip cycles are superimposed on the long‐term loading. We estimate the plate coupling across the subduction zone over three multi‐year observational periods targeting different stages of the slow slip cycle. Our results highlight the importance of the observational time period when interpreting coupling maps, emphasizing the temporal variability of plate coupling. Leveraging multiple geodetic data sets, we demonstrate how InSAR provides powerful constraints on the spatial resolution of both plate coupling and slow fault slip, even in a region where a dense GNSS network exists.

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Interseismic coupling along the Mexican subduction zone seen by InSAR and GNSS

Cited by 13 publications

References 43 publications

Subdaily Slow Fault Slip Dynamics Captured by Low‐Frequency Earthquakes

Subdaily Slow Fault Slip Dynamics Captured by Low‐Frequency Earthquakes

The Mechanisms of Tsunami Amplification and the Earthquake Source of the 2021 M7 Acapulco, Mexico, Earthquake

Imaging the Spatiotemporal Evolution of Plate Coupling With Interferometric Radar (InSAR) in the Hikurangi Subduction Zone

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