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Published March 2019 | Published
Journal Article Open

Coherence-based approaches for estimating the composition of the seismic wavefield

Abstract

As new techniques exploiting the Earth's ambient seismic noise field are developed and applied, such as for the observation of temporal changes in seismic velocity structure, it is crucial to quantify the precision with which wave‐type measurements can be made. This work uses array data at the Homestake mine in Lead, South Dakota, and an array at Sweetwater, Texas, to consider two aspects that control this precision: the types of seismic wave contributing to the ambient noise field at microseism frequencies and the effect of array geometry. Both are quantified using measurements of wavefield coherence between stations in combination with Wiener filters. We find a strong seasonal change between body‐wave and surface‐wave content. Regarding the inclusion of underground stations, we quantify the lower limit to which the ambient noise field can be characterized and reproduced; the applications of the Wiener filters are about 4 times more successful in reproducing ambient noise waveforms when underground stations are included in the array, resulting in predictions of seismic time series with less than a 1% residual, and are ultimately limited by the geometry and aperture of the array, as well as by temporal variations in the seismic field. We discuss the implications of these results for the geophysics community performing ambient seismic noise studies, as well as for the cancellation of seismic Newtonian gravity noise in ground‐based, sub‐Hertz, gravitational‐wave detectors.

Additional Information

© 2019 American Geophysical Union. Received 23 AUG 2018; Accepted 5MAR 2019; Accepted article online 12MAR 2019; Published online 25MAR 2019. Data used in this project are available from the Incorporated Research Institutions for Seismology (IRIS; Mandic et al., 2014). The seismic instruments used for this array were provided by IRIS through the PASSCAL Instrument Center at New Mexico Tech. We thank Nicholas Harmon and an anonymous reviewer for suggestions and improvements to the text. M. C. was supported by the David and Ellen Lee Postdoctoral Fellowship at the California Institute of Technology. We thank the staff at the Sanford Underground Research Facility and PASSCAL for assistance, particularly the help of Tom Regan, Jaret Heise, Jamey Tollefson, and Bryce Pietzyk. This work was supported by National Science Foundation INSPIRE grant PHY1344265. This paper has been assigned LIGO document number LIGO‐P1700422.

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Created:
August 19, 2023
Modified:
October 20, 2023