Source Mechanism and Rupture Directivity of the 18 May 2009 M(W) 4.6 Inglewood, California, Earthquake

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	Source Mechanism and Rupture Directivity of the 18 May 2009 M(W) 4.6 Inglewood, California, Earthquake
	Luo, Yan ; Tan, Ying ; Wei, Shengji ; Helmberger, Don ; Zhan, Zhongwen ; Ni, Sidao ; Hauksson, Egill ; Chen, Yong
刊名	Bulletin of the Seismological Society of America
	2010
期号	6 页码:3269-3277
中文摘要	On 18 May 2009, an M(w) 4.6 earthquake occurred beneath Inglewood, California, and was widely felt. Though source mechanism and its location suggest that the Newport-Inglewood fault (NIF) may be involved in generating the earthquake, rupture directivity must be modeled to establish the connection between the fault and the earthquake. We first invert for the event's source mechanism and depth with the cut-and-paste method in the long-period band (>5 s). Because of the low velocity shallow sediments in the Los Angeles (LA) basin, we use two velocity models in the inversion for stations inside and outside the LA basin. However, little difference is observed in the resolved source mechanism (M(w) 4.6, strike 246 degrees/145 degrees, dip 50 degrees/77 degrees, rake 17 degrees/138 degrees) and depth (7 to similar to 9 km), compared to an inversion using the standard southern Calfornia model. With the resolved source parameters, we calibrate the amplitude anomaly of the short-period (0.5-2 Hz) P waves with amplitude adjustment factors (AAF). These AAFs are used as corrections when retrieving source mechanisms of the smaller aftershocks using short-period P waves alone. Most of the aftershocks show similar source mechanisms as that of the mainshock, providing ideal empirical Green's functions (EGFs) for studying its rupture process. We use a forward modeling approach to retrieve rupture directivity of the mainshock, consistent with movement on the NIF with rupture toward the southeast. Although we focus on P waves for analyzing rupture directivity, the resolved unilateral pattern is also confirmed with the azimuthal variation of the duration of SH waves observed in the basin. The high rupture velocity near the shear velocity and relatively low stress drop are consistent with the hypothesis of rupture on a mature fault.
原文出处	://WOS:000284997900026
公开日期	2012-04-11
内容类型	期刊论文
源URL	[http://ir.whigg.ac.cn/handle/342008/3203]
专题	测量与地球物理研究所_其他_期刊论文
推荐引用方式 GB/T 7714	Luo, Yan,Tan, Ying,Wei, Shengji,et al. Source Mechanism and Rupture Directivity of the 18 May 2009 M(W) 4.6 Inglewood, California, Earthquake[J]. Bulletin of the Seismological Society of America,2010(6):3269-3277.
APA	Luo, Yan.,Tan, Ying.,Wei, Shengji.,Helmberger, Don.,Zhan, Zhongwen.,...&Chen, Yong.(2010).Source Mechanism and Rupture Directivity of the 18 May 2009 M(W) 4.6 Inglewood, California, Earthquake.Bulletin of the Seismological Society of America(6),3269-3277.
MLA	Luo, Yan,et al."Source Mechanism and Rupture Directivity of the 18 May 2009 M(W) 4.6 Inglewood, California, Earthquake".Bulletin of the Seismological Society of America .6(2010):3269-3277.