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Frequency-Dependent P Wave Polarization and Its Subwavelength Near-Surface Depth Sensitivity

Park, Sunyoung and Tsai, Victor C. and Ishii, Miaki (2019) Frequency-Dependent P Wave Polarization and Its Subwavelength Near-Surface Depth Sensitivity. Geophysical Research Letters, 46 (24). pp. 14377-14384. ISSN 0094-8276. doi:10.1029/2019gl084892.

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Near‐surface structure is crucial to assessing seismic hazards and understanding earthquakes and surface processes yet is a major challenge to robustly image. Recently, an approach based on body‐wave polarization was introduced for constraining shallow seismic structure, but the depth sensitivity of the polarization measurement has remained unclear. Using waveform simulations based on a layer over a half space, we find that the depth sensitivity of P wave polarization peaks at the surface and decreases abruptly over a depth range shorter than its wavelength. A strong frequency dependence provides constraints on local 1‐D structure, with frequencies between 0.1 and 10 Hz illuminating structure at depths of 10 m to several kilometers. Applying these results to teleseismic recordings in Japan provides constraints on structure at about 120 to 750 m, including a distinctive weak zone along the Median Tectonic Line in the Kii peninsula and Awaji Island.

Item Type:Article
Related URLs:
URLURL TypeDescription
Park, Sunyoung0000-0002-6660-0047
Tsai, Victor C.0000-0003-1809-6672
Additional Information:© 2019 American Geophysical Union. Received 9 AUG 2019; Accepted 8 NOV 2019; Accepted article online 15 NOV 2019. The authors thank the editor Jeroen Ritsema and two anonymous reviewers for helpful comments. S.P. thanks Hiroo Kanamori for valuable discussion about the Median Tectonic Line. The early phase of this work was supported by NSF grant EAR‐1735960. S. P. was also supported by the Caltech Texaco Postdoctoral Fellowship. The waveform simulation code was obtained from QUEST (‐‐method.html).
Group:Seismological Laboratory
Funding AgencyGrant Number
Caltech Texaco Postdoctoral FellowshipUNSPECIFIED
Subject Keywords:body‐wave polarization; depth sensitivity; near‐surface structure; site characterization; seismic hazard assessment; Japan
Issue or Number:24
Record Number:CaltechAUTHORS:20200103-074516932
Persistent URL:
Official Citation:Park, S., Tsai, V. C., & Ishii, M. (2019). Frequency‐dependent P wave polarization and its subwavelength near‐surface depth sensitivity. Geophysical Research Letters, 46, 14377–14384.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100477
Deposited By: Tony Diaz
Deposited On:05 Jan 2020 03:58
Last Modified:16 Nov 2021 17:54

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