Intermittence of transient slow slip in the Mexican subduction zone

Creators: El Yousfi, Zaccaria¹; Radiguet, Mathilde¹; Rousset, Baptiste²; Husker, Allen³; Kazachkina, Ekaterina⁴; Kostoglodov, Vladimir⁴

1. Institut des Sciences de la Terre
2. Institut Terre et Environnement de Strasbourg
3. California Institute of Technology
4. National Autonomous University of Mexico

Abstract

In the Mexican subduction zone, slow slip events of various duration, from a few days to several months have previously been identified in the regions of Guerrero and Oaxaca. They occur along with microseismicity: low-frequency earthquakes and tectonic tremors. In this study, we analyzed a 10-year long tremor catalog covering multiple SSE cycles, to identify periods of high tremor activity. We then used the temporal information of these tremor bursts to decompose GNSS time series. Surface velocities estimated for tremor and non-tremor periods are then inverted to locate slip rates on the plate interface. Combining the detected microseismicity information and GNSS time series, we show that large slow slip events are made of clusters of short-lasting slip events occurring at tremor times and located updip of the tremor area. This analysis also allowed us to unveil low amplitude transients in between large slow slip events, that last 8 − 9 days, occurring at tremor times and locations, in both Guerrero and Oaxaca regions. Finally, we show that the plate locking amplitude in between short and large slow slip events increases by a factor up to 0.5 at the location of tremors.

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Acknowledgement

We thank people who maintain the cGPS networks in Guerrero (IG-UNAM) and Oaxaca (TLALOCNet program) states, in particular J. A. Santiago at the Servicio Mareografico Nacional-UNAM, S. I. Franco at the Servicio Sismologico Nacional-UNAM. This study has been supported by the Agence Nationale de la Recherche (ANR-21-CE49-0023) SSDYN project, and by the Universidad Nacional Autónoma de México PAPIIT-IG100921 project. We also thank William Frank for discussion and comparison with his work, and Yuji Itoh for discussion about GNSS time series decomposition.

Contributions

Zaccaria El Yousfi: Writing – original draft, Software, Investigation. Mathilde Radiguet: Writing – review & editing, Supervision, Conceptualization. Baptiste Rousset: Writing – review & editing, Supervision. Allen Husker: Writing – review & editing. Ekaterina Kazachkina: Data curation. Vladimir Kostoglodov: Writing – review & editing.

Data Availability

The authors do not have permission to share data.

Supplemental Material

MMC 1. Bursts ARIG.txt contain the tremor bursts start and end times for the seismic stations ARIG. The first columns correspond to the start times of the second ones to the end time. (TXT)

MMC 2. Bursts PLIG.txt contain the tremor bursts start and end times for the seismic stations PLIG. The first columns correspond to the start times of the second ones to the end time. (TXT)

MMC 3. Bursts TXIG.txt contain the tremor bursts start and end times for the seismic stations TXIG. The first columns correspond to the start times of the second ones to the end time. (TXT)

MMC 4. Bursts YOIG.txt contain the tremor bursts start and end times for the seismic stations YOIG. The first columns correspond to the start times of the second ones to the end time. (TXT)

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