Tremor-genic slow slip regions may be deeper and warmer and may slip slower than non-tremor-genic regions

Geochemistry, Geophysics, Geosystems
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Abstract

Slow slip events (SSEs) are observed worldwide and often coincide with tectonic tremor. Notable examples of SSEs lacking observed tectonic tremor, however, occur beneath Kīlauea Volcano, Hawaii, the Boso Peninsula, Japan, near San Juan Bautista on the San Andreas Fault, California, and recently in Central Ecuador. These SSEs are similar to other worldwide SSEs in many ways (e.g., size or duration), but lack the concurrent tectonic tremor observed elsewhere; instead, they trigger swarms of regular earthquakes. We investigate the physical conditions that may distinguish these non-tremor-genic SSEs from those associated with tectonic tremor, including slip velocity, pressure, temperature, fluids, and fault asperities, although we cannot eliminate the possibility that tectonic tremor may be obscured in highly attenuating regions. Slip velocities of SSEs at Kīlauea Volcano (∼10−6 m/s) and Boso Peninsula (∼10−7 m/s) are among the fastest SSEs worldwide. Kīlauea Volcano, the Boso Peninsula, and Central Ecuador are also among the shallowest SSEs worldwide, and thus have lower confining pressures and cooler temperatures in their respective slow slip zones. Fluids also likely contribute to tremor generation, and no corresponding zone of high vp/vs has been noted at Kīlauea or Boso. We suggest that the relatively faster slip velocities at Kīlauea Volcano and the Boso Peninsula result from specific physical conditions that may also be responsible for triggering swarms of regular earthquakes adjacent to the slow slip, while different conditions produce slower SSE velocities elsewhere and trigger tectonic tremor.

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Publication type Article
Publication Subtype Journal Article
Title Tremor-genic slow slip regions may be deeper and warmer and may slip slower than non-tremor-genic regions
Series title Geochemistry, Geophysics, Geosystems
DOI 10.1002/2015GC005895
Volume 16
Issue 10
Year Published 2015
Language English
Publisher American Geophysical Union
Publisher location Washington, DC
Contributing office(s) Volcano Science Center
Description 14 p.
First page 3593
Last page 3606
Country Costa Rica, Ecuador, Japan, Mexico, New Zealand, United States
State Alaska, California, Hawaii
Other Geospatial Boso Peninsula, Kīlauea Volcano, San Juan Bautista
Online Only (Y/N) N
Additional Online Files (Y/N) N
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