Slip bursts during coalescence of slow slip events in Cascadia

Blétery, Quentin; Nocquet, Jean‐Mathieu

doi:10.1038/s41467-020-15494-4

Cited by 28 publications

(49 citation statements)

References 35 publications

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“…The merging of two SSEs probably caused local acceleration of fault slip, resulting in intensive LFE activity after the passage of the slip front. A temporal acceleration in slip induced by the merging of two SSEs has been reported along the Cascadia subduction zone based on geodetic measurements (Bletery and Nocquet, 2020), but on a much larger scale.…”

Section: Methodsmentioning

confidence: 93%

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

Kato¹,

Nakagawa²

2020

Preprint

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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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Section: Methodsmentioning

confidence: 93%

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

Kato¹,

Nakagawa²

2020

Preprint

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show abstract

“…In some cases, the nucleation and growth of SST can be rather complex. For example, Bletery & Nocquet [ 69 ] consider a 2013 SST in which tremor and GPS data suggest initial nucleation in three different spots followed by growth and coalescence, over the course of three weeks. As the three slip fronts approach each other and merge, the rate of moment release substantially increases, suggesting that coalescence of multiple SST can lead to a more energetic event [ 69 ].…”

Section: Geophysical Observations Of Sst Environment and Sourcementioning

confidence: 99%

“…For example, Bletery & Nocquet [ 69 ] consider a 2013 SST in which tremor and GPS data suggest initial nucleation in three different spots followed by growth and coalescence, over the course of three weeks. As the three slip fronts approach each other and merge, the rate of moment release substantially increases, suggesting that coalescence of multiple SST can lead to a more energetic event [ 69 ]. Frank et al [ 70 ] evaluate the slip evolution of a long-term SSE inferred from GPS time series and LFE recurrence intervals in the Guerrero subduction zone to develop a conceptual model of updip migrating pore-pressure pulses modulating the slip and strength of the fault zone.…”

Section: Geophysical Observations Of Sst Environment and Sourcementioning

confidence: 99%

What’s down there? The structures, materials and environment of deep-seated slow slip and tremor

Behr

Bürgmann

2021

Phil. Trans. R. Soc. A.

151

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Deep-seated slow slip and tremor (SST), including slow slip events, episodic tremor and slip, and low-frequency earthquakes, occur downdip of the seismogenic zone of numerous subduction megathrusts and plate boundary strike-slip faults. These events represent a fascinating and perplexing mode of fault failure that has greatly broadened our view of earthquake dynamics. In this contribution, we review constraints on SST deformation processes from both geophysical observations of active subduction zones and geological observations of exhumed field analogues. We first provide an overview of what has been learned about the environment, kinematics and dynamics of SST from geodetic and seismologic data. We then describe the materials, deformation mechanisms, and metamorphic and fluid pressure conditions that characterize exhumed rocks from SST source depths. Both the geophysical and geological records strongly suggest the importance of a fluid-rich and high fluid pressure habitat for the SST source region. Additionally, transient deformation features preserved in the rock record, involving combined frictional-viscous shear in regions of mixed lithology and near-lithostatic fluid pressures, may scale with the tremor component of SST. While several open questions remain, it is clear that improved constraints on the materials, environment, structure, and conditions of the plate interface from geophysical imaging and geologic observations will enhance model representations of the boundary conditions and geometry of the SST deformation process. This article is part of a discussion meeting issue ‘Understanding earthquakes using the geological record’.

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Section: Resultsmentioning

confidence: 92%

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

Kato¹,

Nakagawa²

2020

Preprint

View full text Add to dashboard Cite

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.

show abstract

Slip bursts during coalescence of slow slip events in Cascadia

Cited by 28 publications

References 35 publications

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

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

What’s down there? The structures, materials and environment of deep-seated slow slip and tremor

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

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