[1]ZHANG Zhi-wei,ZHANG Yong-jiu,CHENG Wan-Zheng,et al.Focal Mechanisms and Stress Field of Small Earthquakes of the MS8.0 Wenchuan Earthquake Sequence[J].Journal of Seismological Research,2010,33(01):43-49.
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Focal Mechanisms and Stress Field of Small Earthquakes of the MS8.0 Wenchuan Earthquake Sequence
Journal of Seismological Research[ISSN 1000-0666/CN 53-1062/P] Volume:
33
Number of periods:
2010 01
Page number:
43-49
Column:
Public date:
2010-01-01
- Title:
- Focal Mechanisms and Stress Field of Small Earthquakes of the MS8.0 Wenchuan Earthquake Sequence
- CLC:
- P315.3+3
- DOI:
- -
- Abstract:
- Based on the data of digital seismic wave from May 12,2008 to April 12,2009 recorded by regional seismic network,the focal-mechanism solutions of 829 small events with ML≥3.5 of the MS8.0 Wenchuan earthquake sequence were determined by the amplitude ratio of PG and SG in vertical component records with clear initial motion.Using the method of statistical analysis and stress axis tensor,the parameters of focal-mechanism solutions are analyzed and the average stress-field azimuth of aftershock area is calculated.The results show that the source-fracture plane of small earthquakes presents the strike of NNE direction,and the dip angles are near vertical or inclined at northern segment of the Longmenshan fault.The principal direction of compressive stress P-axis is SWW-NEE,the azimuth of maximum principal stress axis is 77.1°.At northern segment of aftershock area,the nodal plane strikes are relatively dispersed.The dip angles are steep,dispersed between 50° and 90°.The azimuth of maximum principal stress axis is EW,that is 92.4°.It can be seen from the evolution process of average stress-field with time at northern and southern segment of aftershock area,that the stress adjustment stages of aftershock area are August,September,December in 2008 and January in 2009.The consistency parameter curve and the proportional change of thrust-type earthquakes with time in the aftershock area are also studied,and then some significant results are given.
- References:
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Last Update:
2010-01-23