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

Slow slip events (SSEs) represent a significant mechanism of strain release along several subduction zones, and understanding their occurrence and relations with major earthquake asperities is essential for a comprehensive understanding of the seismic cycle. Here, we focus on the Mexican subduction zone, characterized by the occurrence of recurrent large slow slip events (SSEs), both in the Guerrero region, where the SSEs are among the largest observed worldwide, and in the Oaxaca region, where smaller, more frequent SSEs occur. Up to now, most slow slip studies in the Mexican subduction zone focused either on the detailed analysis of a single event, were limited to a small area (Guerrero or Oaxaca), or were limited to data before 2012 [e.g.1-4]. In this study, our aim is to build an updated and consistent catalog of major slow slip events in the Guerrero-Oaxaca region.We use an approach similar to Michel et al. 2018 [5]. We analyze the GPS time series from 2000 to 2019 using Independent Component Analysis (ICA), in order to separate temporally varying sources of different origins (seasonal signals, SSEs and afterslip of major earthquakes). We are able to isolate a component corresponding to seasonal loading, which matches the temporal evolution of displacement modeled from the GRACE data. The sources (independent components) identified as tectonic sources of deep origin are inverted for slip on the subduction interface. We thus obtain a model of the spatio-temporal evolution of aseismic slip on the subduction interface over 19 years, from which we can isolate around 30 individual slow slip events of Mw > 6.2.&#160;The obtained catalog is coherent with previous studies (in terms of number of events detected, magnitude and duration) which validates the methodology. The observed moment-duration scaling is close to M0~T3 as recently suggested by Michel [6] for Cascadia SSEs, and our study extends the range of magnitude considered in their analysis. Finally, we also investigate the spatio-temporal relations between the SSEs occurring in the adjacent regions of Guerrero and Oaxaca, and their interaction with local and distant earthquakes.&#160;References:<ol><li>Kostoglodov, V. et al. A large silent earthquake in the Guerrero seismic gap, Mexico. Geophys. Res. Lett 30, 1807 (2003).</li> <li>Graham, S. et al. Slow Slip History for the Mexico Subduction Zone: 2005 Through 2011. Pure and Applied Geophysics 1&#8211;21 (2015). doi:10.1007/s00024-015-1211-x</li> <li>Larson, K. M., Kostoglodov, V. & Shin&#8217;ichi Miyazaki, J. A. S. The 2006 aseismic slow slip event in Guerrero, Mexico: New results from GPS. Geophys. Res. Lett. 34, L13309 (2007).</li> <li>Radiguet, M. et al. Slow slip events and strain accumulation in the Guerrero gap, Mexico. J. Geophys. Res. 117, B04305 (2012).</li> <li>Michel, S., Gualandi, A. & Avouac, J.-P. Interseismic Coupling and Slow Slip Events on the Cascadia Megathrust. Pure Appl. Geophys. (2018). doi:10.1007/s00024-018-1991-x</li> <li>Michel, S., Gualandi, A. & Avouac, J. Similar scaling laws for earthquakes and Cascadia slow-slip events. Nature 574, 522&#8211;526 (2019) doi:10.1038/s41586-019-1673-6</li> </ol>&#160;

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Long-term slow slip events along the Nankai trough subduction zone after the 2011 Tohoku earthquake in Japan

Earth Planets and Space ◽

10.1186/s40623-017-0640-4 ◽

2017 ◽

Vol 69 (1) ◽

Cited By ~ 16

Author(s):

Shinzaburo Ozawa

Keyword(s):

Subduction Zone ◽

Nankai Trough ◽

Tohoku Earthquake ◽

2011 Tohoku Earthquake ◽

Slow Slip ◽

The 2011 Tohoku Earthquake ◽

Slow Slip Events

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Detection of Deep Low-frequency Earthquakes in the Nankai Subduction Zoneover 11 Years Usingamatched Filter Technique

10.21203/rs.3.rs-37377/v1 ◽

2020 ◽

Author(s):

Aitaro Kato ◽

Shigeki Nakagawa

Keyword(s):

Matched Filter ◽

Low Frequency ◽

Slow Slip ◽

Slow Slip Events ◽

Filter Technique ◽

Strike Direction ◽

Episodic Tremor And Slip ◽

Spatio Temporal ◽

Episodic Tremor

Abstract To improve our understanding of the long-term behavior of low-frequency earthquakes (LFEs) along the tremor belt of the Nankai subduction zone, we applied a matched filter technique to continuous seismic data recorded by a dense and highly sensitive seismic network over an 11year window, April 2004 to August 2015. We detected a total of ~510,000 LFEs, or ~23× the number of LFEs in the JMA catalog for the same period. During long-term slow slip events (SSEs) in the Bungo Channel, a series of migrating LFEbursts intermittently occurred along the fault-strike direction, with slow hypocenter propagation. Elastic energy released by long-term SSEs appears to control the extent of LFE activity. We identify slowlymigrating fronts of LFEs during major episodic tremor and slip (ETS)events, which extend over distances of up to 100 km and follow diffusion-like patterns of spatial evolution with a diffusion coefficient of ~104 m2/s. This migration pattern closely matches the spatio-temporal evolution of tectonictremors reported by previous studies. At shorter distances, up to 15 km, we discovered rapid diffusion-like migrationof LFEs with a coefficient of ~105 m2/s. We also recognize that rapid migration of LFEs occurred intermittently in many streaks during major ETS episodes. These observations suggest that slow slip transients contain a multitude of smaller, temporally clustered fault slip events whose evolution is controlled by a diffusional process.

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Localized seismic anisotropy associated with long-term slow-slip events beneath southern Mexico

Geophysical Research Letters ◽

10.1029/2012gl051324 ◽

2012 ◽

Vol 39 (9) ◽

pp. n/a-n/a ◽

Cited By ~ 19

Author(s):

Teh-Ru Alex Song ◽

YoungHee Kim

Keyword(s):

Seismic Anisotropy ◽

Slow Slip ◽

Southern Mexico ◽

Slow Slip Events

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Detection of deep low-frequency earthquakes in the Nankai subduction zone over 11 years using a matched filter technique

10.21203/rs.3.rs-37377/v2 ◽

2020 ◽

Author(s):

Aitaro Kato ◽

Shigeki Nakagawa

Keyword(s):

Subduction Zone ◽

Matched Filter ◽

Low Frequency ◽

Slow Slip ◽

Slow Slip Events ◽

Filter Technique ◽

Episodic Tremor And Slip ◽

Nankai Subduction Zone ◽

Spatio Temporal

Abstract To improve our understanding of the long-term behavior of low-frequency earthquakes (LFEs) along the tremor belt of the Nankai subduction zone, we applied a matched filter technique to continuous seismic data recorded by a dense and highly sensitive seismic network over an 11 year window, April 2004 to August 2015. We detected a total of ~510,000 LFEs, or ~23× the number of LFEs in the JMA catalog for the same period. During long-term slow slip events (SSEs) in the Bungo Channel, a series of migrating LFE bursts intermittently occurred along the fault-strike direction, with slow hypocenter propagation. Elastic energy released by long-term SSEs appears to control the extent of LFE activity. We identify slowly migrating fronts of LFEs during major episodic tremor and slip (ETS) events, which extend over distances of up to 100 km and follow diffusion-like patterns of spatial evolution with a diffusion coefficient of ~10 4 m 2 /s. This migration pattern closely matches the spatio-temporal evolution of tectonic tremors reported by previous studies. At shorter distances, up to 15 km, we discovered rapid diffusion-like migration of LFEs with a coefficient of ~10 5 m 2 /s. We also recognize that rapid migration of LFEs occurred intermittently in many streaks during major ETS episodes. These observations suggest that slow slip transients contain a multitude of smaller, temporally clustered fault slip events whose evolution is controlled by a diffusional process.

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