气候变化领域集成服务门户(CCPortal): Shallow Basin Structure and Attenuation Are Key to Predicting Long Shaking Duration in Los Angeles Basin

CCPortal

DOI	10.1029/2020JB019663
	Shallow Basin Structure and Attenuation Are Key to Predicting Long Shaking Duration in Los Angeles Basin
	Lai V.H.; Graves R.W.; Yu C.; Zhan Z.; Helmberger D.V.
发表日期	2020
ISSN	21699313
卷号	125 期号:10
英文摘要	Ground motions in the Los Angeles Basin during large earthquakes are modulated by earthquake ruptures, path effects into the basin, basin effects, and local site response. We analyzed the direct effect of shallow basin structures on shaking duration at a period of 2–10 s in the Los Angeles region through modeling small magnitude, shallow, and deep earthquake pairs. The source depth modulates the basin response, particularly the shaking duration, and these features are a function of path effect and not site condition. Three-dimensional simulations using the CVM-S4.26.M01 velocity model show good fitting to the initial portion of the waveforms at periods of 5 s and longer but fail to predict the long shaking duration during shallow events, especially at periods less than 5 s. Simulations using CVM-H do not match the timing of the initial arrivals as well as CVM-S4.26.M01, and the strong late arrivals in the CVM-H simulation travel with an apparent velocity slower than observed. A higher-quality factor than traditionally assumed may produce synthetics with longer durations but is unable to accurately match the amplitude and phase. Beamforming analysis using dense array data further reveals the long duration surface waves have the same back azimuth as the direct arrivals and are generated at the basin edges, while the later coda waves are scattered from off-azimuth directions, potentially due to strong, sharp boundaries offshore. Improving the description of these shallow basin structures and attenuation model will enhance our capability to predict long-period ground motions in basins. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	attenuation; community velocity model; dense array; ground motion; Los Angeles basin; waveform simulation
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/187581
作者单位	Seismological Laboratory, California Institute of Technology, Pasadena, CA, United States; Research School of Earth Sciences, Australian National University, Acton, ACT, Australia; U.S. Geological Survey, Pasadena, CA, United States; Department of Earth Space Sciences, Southern University of Science and Technology, Shenzhen, China
推荐引用方式 GB/T 7714	Lai V.H.,Graves R.W.,Yu C.,et al. Shallow Basin Structure and Attenuation Are Key to Predicting Long Shaking Duration in Los Angeles Basin[J],2020,125(10).
APA	Lai V.H.,Graves R.W.,Yu C.,Zhan Z.,&Helmberger D.V..(2020).Shallow Basin Structure and Attenuation Are Key to Predicting Long Shaking Duration in Los Angeles Basin.Journal of Geophysical Research: Solid Earth,125(10).
MLA	Lai V.H.,et al."Shallow Basin Structure and Attenuation Are Key to Predicting Long Shaking Duration in Los Angeles Basin".Journal of Geophysical Research: Solid Earth 125.10(2020).