Changes of Event Size Distribution During Episodes of Shallow Tectonic Tremor, Nankai Trough

Yabe, Suguru

doi:10.1029/2020gl092011

Cited by 3 publications

(1 citation statement)

References 67 publications

(103 reference statements)

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“…(b) Tremor swarms, on the other hand, behave with an earthquake‐like frequency magnitude distribution with b values near 1. This is in agreement numerous studies from Japan (e.g., Nakano & Yabe, 2021), the San Andreas Fault (e.g., Staudenmaier et al., 2019), and Cascadia (e.g., Bostock et al., 2015; Wech et al., 2010) that have shown various slow earthquake phenomena to follow a power‐law size distribution. An exponential taper does fit the swarm data slightly better as well, but only at the very upper end of the distribution.…”

Section: Discussionsupporting

confidence: 90%

Cataloging Tectonic Tremor Energy Radiation in the Cascadia Subduction Zone

Wech

2021

JGR Solid Earth

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Aseismic processes are increasingly recognized as a fundamental part of plate boundary dynamics and the earthquake cycle. These processes generate a broad range of geodetic and seismic signals, including tectonic tremor (Obara, 2002), which has been observed in numerous subduction zones worldwide (e.g., Ide, 2012). These persistent, low-frequency seismic signals can last days to weeks, coinciding with slow slip at the megathrust plate boundary (Rogers & Dragert, 2003), but they also occur in shorter bursts that likely reflect slip occurring below geodetic resolution (e.g., Wech et al., 2010). These events represent valuable scientific targets for improving our understanding of fault conditions, slip processes and earthquake rupture dynamics, and are a focus of seismic and geodetic monitoring to track potential long-term and time-dependent hazards associated with their occurrence. Documenting when, where and how much tremor occurs provides a basis for investigating tremor and slip behavior. Many studies have documented and characterized spatiotemporal patterns of tectonic tremor activity, including how it relates to geodetically observed slow slip events (SSEs) (e.g., Bartlow et al., 2011;

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Section: Discussionsupporting

confidence: 90%

Cataloging Tectonic Tremor Energy Radiation in the Cascadia Subduction Zone

Wech

2021

JGR Solid Earth

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Model for tectonic tremors: Enduring events, moment rate spectrum, and moment-duration scaling

2022

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A review of shallow slow earthquakes along the Nankai Trough

Takemura,

Hamada,

Okuda

et al. 2023

Earth Planets Space

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Slow earthquakes occur at deep and shallow plate boundaries along the Nankai Trough. Deep slow earthquakes are continuously distributed along the 30–40 km depth contours of the upper surface of the subducted Philippine Sea Plate. In contrast, shallow slow earthquakes occur in limited regions: Hyuga-nada, off Cape Muroto, and southeast off the Kii Peninsula. This review provides an overview of the up-to-date seismological, geodetic, geological, and experimental results in the shallow Nankai area for a unified understanding of the spot-like occurrence of shallow slow earthquakes. Shallow slow earthquakes tend to be distributed in transitional regions between the frictionally locked and stably sliding zones on the plate boundary. Based on geological and experimental studies, the lithology of incoming sediments and their friction coefficients can be variable along the Nankai Trough. Laboratory friction experiments revealed that sediments under shallow plate boundary conditions often exhibit positive (a − b) values, while negative (a − b) is possible via several processes. Subducted seamounts create complex fracture networks and stress shadows in their surrounding areas; however, not all subducted seamounts are related to shallow slow earthquake activities. This incomplete correlation suggests that alternative factors are required to explain the spot-like distribution of shallow slow earthquakes in the Nankai subduction zone. High pore fluid pressure conditions around shallow slow earthquake zones were interpreted based on seismological structural studies. In addition, ambient noise monitoring revealed temporal changes in seismic velocity structures associated with shallow slow earthquake migrations. This result suggests a close link between pore fluid migration and shallow slow earthquake episodes. Because transient changes in pore fluid pressure can lead to various slip behaviors, the episodic migration of pore fluid around the plate boundary could promote shallow slow earthquake activity along the Nankai Trough. Graphical Abstract

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Changes of Event Size Distribution During Episodes of Shallow Tectonic Tremor, Nankai Trough

Cited by 3 publications

References 67 publications

Cataloging Tectonic Tremor Energy Radiation in the Cascadia Subduction Zone

Cataloging Tectonic Tremor Energy Radiation in the Cascadia Subduction Zone

Model for tectonic tremors: Enduring events, moment rate spectrum, and moment-duration scaling

A review of shallow slow earthquakes along the Nankai Trough

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