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Denoising surface waves extracted from ambient noise using three-station interferometry: Methodology and application to 1-D linear array
  • Hongrui Qiu,
  • Fenglin Niu,
  • Lei Qin
Hongrui Qiu
Rice University

Corresponding Author:[email protected]

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Fenglin Niu
Rice University
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Lei Qin
University of Southern California
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Abstract

We develop an automatic workflow for denoising the fundamental mode surface wave from ambient noise cross correlations (ANCs) calculated for a dense linear array. The surface wave signal traveling between each station pair is first enhanced through three-station interferometry. Then, phase travel times at different periods are determined in the frequency domain. The proposed array-based method is applied to a 1.6-km-long dense linear nodal array crossing surface traces of the San Jacinto fault near Anza, California. Surface wave signals in ANCs of the nodal array are significantly enhanced after denoising, particularly at high frequencies (> 2 Hz). Phase travel times are extracted reliably in the period ranges of 0.3-1.3 s and 0.3-1.6 s for Rayleigh and Love waves, respectively. The corresponding period-dependent phase velocity profiles derived from the eikonal equation reveal high-resolution details of fault zone internal structures beneath the array. A broad (500-1000 m) low-velocity zone that narrows with increasing period is observed, illuminating a flower-shaped structure of the San Jacinto fault damage zone.