Slab morphology in the Cascadia fore arc and its relation to episodic tremor and slip

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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DO SMALL FAULTS IN THE BARABOO SYNCLINE PRESERVE EVIDENCE OF EPISODIC TREMOR AND SLIP (ETS)?

10.1130/abs/2018am-319069 ◽

2018 ◽

Author(s):

Allison D. Jones ◽

◽

Laurel B. Goodwin ◽

Philip E. Brown

Keyword(s):

Episodic Tremor And Slip ◽

Episodic Tremor

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Repeating earthquakes, episodic tremor and slip: Emerging patterns in complex earthquake cycles?

Complexity ◽

10.1002/cplx.20185 ◽

2007 ◽

Vol 12 (5) ◽

pp. 33-43 ◽

Cited By ~ 4

Author(s):

Wang-Ping Chen ◽

Michael R. Brudzinski

Keyword(s):

Repeating Earthquakes ◽

Emerging Patterns ◽

Episodic Tremor And Slip ◽

Episodic Tremor ◽

Earthquake Cycles

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Episodic Tremor and Slip (ETS) as a chaotic multiphysics spring

Physics of The Earth and Planetary Interiors ◽

10.1016/j.pepi.2016.10.002 ◽

2017 ◽

Vol 264 ◽

pp. 20-34 ◽

Cited By ~ 5

Author(s):

E. Veveakis ◽

S. Alevizos ◽

T. Poulet

Keyword(s):

Episodic Tremor And Slip ◽

Episodic Tremor

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Model of Deep Nonvolcanic Tremor Part II: Episodic Tremor and Slip

Bulletin of the Seismological Society of America ◽

10.1785/0120140225 ◽

2015 ◽

Vol 105 (2A) ◽

pp. 816-830 ◽

Cited By ~ 3

Author(s):

Naum I. Gershenzon ◽

Gust Bambakidis

Keyword(s):

Episodic Tremor And Slip ◽

Episodic Tremor

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Melting of subducted sediments reconciles geophysical images of subduction zones

Nature Communications ◽

10.1038/s41467-021-21657-8 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

M. W. Förster ◽

K. Selway

Keyword(s):

Subduction Zones ◽

Source Region ◽

Volcanic Rocks ◽

Electrically Conductive ◽

Small Magnitude ◽

Volcanic Arcs ◽

Frictional Strength ◽

Episodic Tremor And Slip ◽

Episodic Tremor ◽

Sediment Melting

AbstractSediments play a key role in subduction. They help control the chemistry of arc volcanoes and the location of seismic hazards. Here, we present a new model describing the fate of subducted sediments that explains magnetotelluric models of subduction zones, which commonly show an enigmatic conductive anomaly at the trenchward side of volcanic arcs. In many subduction zones, sediments will melt trenchward of the source region for arc melts. High-pressure experiments show that these sediment melts will react with the overlying mantle wedge to produce electrically conductive phlogopite pyroxenites. Modelling of the Cascadia and Kyushu subduction zones shows that the products of sediment melting closely reproduce the magnetotelluric observations. Melting of subducted sediments can also explain K-rich volcanic rocks that are produced when the phlogopite pyroxenites melt during slab roll-back events. This process may also help constrain models for subduction zone seismicity. Since melts and phlogopite both have low frictional strength, damaging thrust earthquakes are unlikely to occur in the vicinity of the melting sediments, while increased fluid pressures may promote the occurrence of small magnitude earthquakes and episodic tremor and slip.

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