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Sources of Long‐Range Anthropogenic Noise in Southern California and Implications for Tectonic Tremor Detection

Inbal, Asaf and Cristea-Platon, Tudor and Ampuero, Jean-Paul and Hillers, Gregor and Agnew, Duncan and Hough, Susan E. (2018) Sources of Long‐Range Anthropogenic Noise in Southern California and Implications for Tectonic Tremor Detection. Bulletin of the Seismological Society of America, 108 (6). pp. 3511-3527. ISSN 0037-1106. doi:10.1785/0120180130.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Inbal, Asaf0000-0001-8848-7279
Ampuero, Jean-Paul0000-0002-4827-7987
Hough, Susan E.0000-0002-5980-2986
Additional Information:© 2018 Seismological Society of America. Manuscript received 28 April 2018; Published Online 16 October 2018. The authors thank D. Shelly, A. Barbour, N. Lindsey, and an anonymous reviewer for thoughtful reviews that improved this article. A. Inbal wishes to thank R. C. Escamilla for pointing out the La Rumorosa wind farm project as a potential source of seismic noise in Anza and A. Vidal and A. Nuñez from the Centro de Investigación Cientifica y de Educacion Superior de Ensenada Baja California for their help. Part of A. Inbal’s work was done during a visit to Caltech supported by a scholarship from Ben Gurion University of the Negev, Israel, and by a Fulbright scholarship. Part of A. Inbal’s work at the University of California, Berkeley, was supported by a fellowship from the Israeli Minister of Energy and Water. T. Cristea‐Platon’s work was supported by the Caltech SURF Program. The MAOTECTRA deployment was funded by U.S. Geological Survey (USGS) Award G11AP20056. This work was partially funded by National Science Foundation (NSF) Grant Number EAR‐1015698 and by the Southern California Earthquake Center (SCEC; Contribution Number 8204). SCEC is funded by NSF Cooperative Agreement EAR‐1033462 and USGS Cooperative Agreement G12AC20038.
Group:Seismological Laboratory
Funding AgencyGrant Number
University of NegevUNSPECIFIED
Fulbright FoundationUNSPECIFIED
Ministry of Energy and Water (Israel)UNSPECIFIED
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Southern California Earthquake Center (SCEC)UNSPECIFIED
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center8204
Issue or Number:6
Record Number:CaltechAUTHORS:20181026-075847829
Persistent URL:
Official Citation:Asaf Inbal, Tudor Cristea‐Platon, Jean‐Paul Ampuero, Gregor Hillers, Duncan Agnew, Susan E. Hough; Sources of Long‐Range Anthropogenic Noise in Southern California and Implications for Tectonic Tremor Detection. Bulletin of the Seismological Society of America ; 108 (6): 3511–3527. doi:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90421
Deposited By: Tony Diaz
Deposited On:26 Oct 2018 16:38
Last Modified:16 Nov 2021 03:32

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