Based on the records of 6 stations in Jiangxi regional seismic network and CSN, we obtained the focal mechanisms of the Ms 5.7 Jiujiang-Ruichang earthquake and its Ms 4.8 aftershock of Nov.26, 2005 with the "Cut and Paste" (CAP) method, and analyzed the seismogenic structure combining with relocation of the aftershock sequence and the geologic settings in the region. Our result shows that the best double couple solution of the Ms 5.7 event is 324°, 55°and 18° for strike, dip and rake angles respectively, the other nodal plane is 223°, 75° and 144°; for the Ms 4.8 aftershock the solution is 54°, 71°, - 160° respectively with the other nodal plane of 317°, 71° and - 20°. Complexities can be found from aftershock distribution and source depth of the sequence. After the occurrence of the Ms 5.7 main shock, aftershocks occurred and propagated from SE to NW and from shallower to deeper crust, then they probably encountered an asperity and triggered the Ms 4.8 strong aftershock. This complexity and the different focal mechanisms imply that the two earthquakes may not occur on the same fault, we infer that the Ms 5.7 main shock is caused by the NW striking Yangjishan-Wushan-Tongjiangling fault buried in Ruichang basin and the Ms 4.8 aftershock occurred on the NE striking Dingjiashan-Guilinqiao-Wuning fault in the northwest margin of the basin.
|Number of pages||7|
|Journal||Chinese Journal of Geophysics|
|Publication status||Published - Jan 2008|
- CAP method
- Focal mechanism
- Jiujiang-Ruichang earthquake
- Seismogenic structure