气候变化领域集成服务门户(CCPortal): Calibrating Spectral Decomposition of Local Earthquakes Using Borehole Seismic Records—Results for the 1992 Big Bear Aftershocks in Southern California

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DOI	10.1029/2020JB020561
	Calibrating Spectral Decomposition of Local Earthquakes Using Borehole Seismic Records—Results for the 1992 Big Bear Aftershocks in Southern California
	Shearer P.M.; Abercrombie R.E.
发表日期	2021
ISSN	21699313
卷号	126 期号:3
英文摘要	Empirical approaches are often used to correct earthquake spectra for path effects in order to estimate corner frequencies and stress drops, but suffer from tradeoffs among source parameters and the shape of the empirical correction or Green's function. This hampers absolute stress-drop estimates and comparisons between different studies or regions. Borehole records are less affected by site and attenuation effects than surface seismometers and thus provide more direct constraints on source spectra. We analyze 1,787 earthquakes of the 1992 to 1993 Big Bear aftershock sequence in southern California, which were recorded by both the Southern California Seismic Network (SCSN) and the Cajon Pass borehole seismometer at 2.5-km depth. Spectral decomposition of P-waves recorded by the SCSN yields source terms that can be fit equally well by a variety of models, owing to tradeoffs between the model parameters and the empirical correction term. Earthquake spectra recorded by the Cajon Pass borehole are consistent with a P-wave Q of about 1,000. For 25 Big Bear earthquakes in common, we find the correction spectrum that brings the event terms from spectral decomposition and the Q-corrected borehole spectra into best-fitting agreement. This provides absolute calibration for the SCSN spectral decomposition results, which can then be used to process all the Big Bear earthquakes and estimate earthquake source properties without the parameter tradeoffs normally associated with the EGF approach. Our results highlight the limits of purely empirical approaches to spectral analysis for earthquake source properties and the importance of determining crustal attenuation models. © 2021. American Geophysical Union. All Rights Reserved.
英文关键词	Cajon Pass borehole; earthquake stress drop; empirical Green's function; spectral decomposition
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187281
作者单位	Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, United States; Department of Earth and Environment, Boston University, Boston, MA, United States
推荐引用方式 GB/T 7714	Shearer P.M.,Abercrombie R.E.. Calibrating Spectral Decomposition of Local Earthquakes Using Borehole Seismic Records—Results for the 1992 Big Bear Aftershocks in Southern California[J],2021,126(3).
APA	Shearer P.M.,&Abercrombie R.E..(2021).Calibrating Spectral Decomposition of Local Earthquakes Using Borehole Seismic Records—Results for the 1992 Big Bear Aftershocks in Southern California.Journal of Geophysical Research: Solid Earth,126(3).
MLA	Shearer P.M.,et al."Calibrating Spectral Decomposition of Local Earthquakes Using Borehole Seismic Records—Results for the 1992 Big Bear Aftershocks in Southern California".Journal of Geophysical Research: Solid Earth 126.3(2021).