黄建平,倪四道,傅容珊等.综合近震及远震波形反演2006文安地震(Mw5. 1) 的震源机制解.地球物理学报

Translated title of the contribution: Source mechanism of the 2006 Mw5.1 Wen'an Earthquake determined from a joint inversion of local and teleseismic broadband waveform data

Jian Ping Huang*, Si Dao Ni, Rong Shan Fu, Feng Lin Niu, Zhi Gang Shao, Yong Zheng

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

On July 4, 2006, a magnitude 5. 1 earthquake occurred at Wen'an, ∼100 km south of Beijing, which was felt in Beijing metropolitan area. To better understand the regional tectonics, we have inverted local and teleseismic broadband waveform data to determine the focal mechanism of this earthquake. We selected waveform data of 9 stations from the recently installed Beijing metropolitan digital Seismic Network (BSN). These stations are located within 600 km and cover a good azimuthal range to the earthquake. To better fit the lower amplitude P waveform, we employed two different weights for the P wave and surface wave arrivals, respectively. A grid search method was employed to find the strike, dip and slip of the earthquake that best fit the three-component records of P and surface waveforms recorded (the tangential component of the Pwave arrivals was not used). Synthetic waveforms were computed with an F-K method. Two crustal velocity models were used in the synthetic calculation to reflect a rapid east-west transition in crustal structure observed by seismic and geological studies in the study area. The 3D grid search results in reasonable constraints on the fault geometry and the slip vector with a less well determined focal depth. As such we combined teleseismic waveform data from 8 stations of the Global Seismic Network in a joint inversion. Clearly identifiable depth phases (pP, sP) recorded by the teleseismic stations obviously provided a better constraint on the resulting source depth. The results from the joint inversion indicate that the Wen'an earthquake is mainly a right-lateral strike slip event ( -150°) which occurred on a near vertical (dip, ∼80°) NNE trending (210°) fault. The estimated focal depth is 14-15 km, and the moment magnitude is 5. 1. The estimated fault geometry here agrees well with aftershock distribution and is consistent with the major fault systems in the area which were developed under a NNE-SSW oriented compressional stress field.

Original languageChinese
Pages (from-to)120-130
Number of pages11
JournalChinese Journal of Geophysics
Volume52
Issue number1
Publication statusPublished - Jan 2009
Externally publishedYes

Keywords

  • Aftershocks distribution
  • Cut and paste method
  • Grid search method
  • Source mechanism
  • Waveform modeling method

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