Sources of long-range anthropogenic noise in southern California and implications for tectonic tremor detection

Bulletin of the Seismological Society of America
By: , and 

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Abstract

We study anthropogenic noise sources seen on seismic recordings along the central section of the San Jacinto fault near Anza, southern California. The strongest signals are caused by freight trains passing through the Coachella Valley north of Anza. Train‐induced transients are observed at distances of up to 50 km from the railway, with durations of up to 20 min, and spectra that are peaked between 3 and 5 Hz. Additionally, truck traffic through the Coachella Valley generates a sustained hum with a similar spectral signature as the train transients but with lower amplitude. We also find that wind turbine activity in northern Baja California introduces a seasonal modulation of 1– to 5‐Hz energy across the Anza network. We show that the observed train‐generated transients can be used to constrain shallow attenuation structure at Anza. Using the results from this study as well as available borehole data, we further evaluate the performance of approaches that have been used to detect nonvolcanic tremor at Anza. We conclude that signals previously identified as spontaneous tremor (Hutchison and Ghosh, 2017) were probably generated by other nontectonic sources such as trains.

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Publication type Article
Publication Subtype Journal Article
Title Sources of long-range anthropogenic noise in southern California and implications for tectonic tremor detection
Series title Bulletin of the Seismological Society of America
DOI 10.1785/0120180130
Volume 108
Issue 6
Publication Date October 16, 2018
Year Published 2018
Language English
Publisher Seismological Society of America
Contributing office(s) Earthquake Science Center
Description 17 p.
First page 3511
Last page 3527
Country United States
State California
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