Imaging a crustal low-velocity layer using reflected seismic waves from the 2014 earthquake swarm at Long Valley Caldera, California: The magmatic system roof?

Geophysical Research Letters
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Abstract

The waveforms generated by the 2014 Long Valley Caldera earthquake swarm recorded at station MLH show clear reflected waves that are often stronger than direct P and S waves. With waveform analyses, we discover that these waves are reflected at the top of a low-velocity body, which may be residual magma from the ∼767 ka caldera-forming eruption. The polarity of the reflection compared to direct P and S waves suggests that the reflection is SP waves (S from hypocenters to reflector and then convert to P waves to the surface). Because the wavefields are coherent among different earthquakes and hold high signal-to-noise ratios, we apply them to a wavefield migration method for imaging reflectors. The depth of the imaged magmatic system roof is around 8.2 km below the surface. This is consistent with previous studies. Even though we use only one station and waveforms from one earthquake swarm, the dense cluster of accurately located earthquakes provides a high-resolution image of the roof.

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Publication type Article
Publication Subtype Journal Article
Title Imaging a crustal low-velocity layer using reflected seismic waves from the 2014 earthquake swarm at Long Valley Caldera, California: The magmatic system roof?
Series title Geophysical Research Letters
DOI 10.1029/2018GL077260
Volume 45
Issue 8
Year Published 2018
Language English
Publisher American Geophysical Union
Contributing office(s) Geologic Hazards Science Center, Volcano Science Center
Description 8 p.
First page 3481
Last page 3488
Country United States
State California
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