Based on the seismic station data sets from Sichuan and Yunnan provinces,we employed a multi-step seismic location method( Hypo2000 + Velest + HypoDD) to precisely locate the 7,787 earthquakes that occurred during 201...Based on the seismic station data sets from Sichuan and Yunnan provinces,we employed a multi-step seismic location method( Hypo2000 + Velest + HypoDD) to precisely locate the 7,787 earthquakes that occurred during 2010-2015 along the eastern boundaries of the Sichuan-Yunnan rhombic block,namely from southern Dawu to the Qiaojia segment.The final results show that location precision is greatly advanced and epicenter distribution exhibits good consistency with the linear distribution of the seismic faults. Earthquake distribution is quite intensive at the intersection region in the southern segment of the Xianshuihe fault,the Anninghe fault zone,the Xiaojinhe fault zone and the Daliangshan fault zone to the east. The depth profile of seismicity shows a clear stepwise activity along the active seismic fault zones. The profile crossing the faults of the Xianshuihe,Anninghe,and Daliangshan presents a complex interaction among faults near the multiple faults intersection region,Shimian,where the earthquakes are obviously divided into two groups in depth. Earthquakes are very rare at the depth of 15km-20 km,which is consistent with the region of the plastic rheology between 14km-19 km calculated by Zhu Ailan et al.,( 2005).展开更多
The Panzhihua Ms6. 1 earthquake sequence on August 30, 2008 was relocated using the Hypo2000 ＋ HypoDD algorithm with the seismic phase data from the Sichuan and Yunnan regional digital seismic networks, and the resul...The Panzhihua Ms6. 1 earthquake sequence on August 30, 2008 was relocated using the Hypo2000 ＋ HypoDD algorithm with the seismic phase data from the Sichuan and Yunnan regional digital seismic networks, and the results show that the epicenters are distributed in the near NS direction, the length of aftershock concentration zone is about 30kin, and the main shock is about 14km in depth. The depth of the sequence is distributed in the range of 0 -4km and 5 -20km, and the layer of 4 -5kin depth is an apparent earthquake absence layer. The cross-section along the fracture＇s long axis shows there is an irregular seismic gap in the middle segment of the aftershock region, which is the rupture region of 3 the M6 3/4earthquake in 1955, and this earthquake occurred in the south of the gap. We believe that the Panzhihua Ms6. 1 earthquake sequence on August 30, 2008 was a result of rupture of the residual asperity caused by the stress adjustment of the Wenchuan Ms8. 0 earthquake. The other two profiles perpendicular to the long axis show that the focal depth in the north segment is larger and the fault plane dips NW, which is consistent with the dip of the Hongge fault.展开更多
基金funded by Study on the Optimal Time Window of Single Azimuth Angle,the Three-in-one Project of Earthquake Monitoring,Prediction and Scientific Research of China Earthquake Administration(CEA-JC/3JH-162305)the Special Training Project for Youth Talents for Seismic Network,China Earthquake Administration(20150422)
文摘Based on the seismic station data sets from Sichuan and Yunnan provinces,we employed a multi-step seismic location method( Hypo2000 + Velest + HypoDD) to precisely locate the 7,787 earthquakes that occurred during 2010-2015 along the eastern boundaries of the Sichuan-Yunnan rhombic block,namely from southern Dawu to the Qiaojia segment.The final results show that location precision is greatly advanced and epicenter distribution exhibits good consistency with the linear distribution of the seismic faults. Earthquake distribution is quite intensive at the intersection region in the southern segment of the Xianshuihe fault,the Anninghe fault zone,the Xiaojinhe fault zone and the Daliangshan fault zone to the east. The depth profile of seismicity shows a clear stepwise activity along the active seismic fault zones. The profile crossing the faults of the Xianshuihe,Anninghe,and Daliangshan presents a complex interaction among faults near the multiple faults intersection region,Shimian,where the earthquakes are obviously divided into two groups in depth. Earthquakes are very rare at the depth of 15km-20 km,which is consistent with the region of the plastic rheology between 14km-19 km calculated by Zhu Ailan et al.,( 2005).
基金funded jointly by the National Natural Science Foundation of China(40674040,41074062)the scientific investigation project of the M_S 7.0 Lushan earthquakethe special program for seismic network backbones of CEA(20150422)
文摘The Panzhihua Ms6. 1 earthquake sequence on August 30, 2008 was relocated using the Hypo2000 ＋ HypoDD algorithm with the seismic phase data from the Sichuan and Yunnan regional digital seismic networks, and the results show that the epicenters are distributed in the near NS direction, the length of aftershock concentration zone is about 30kin, and the main shock is about 14km in depth. The depth of the sequence is distributed in the range of 0 -4km and 5 -20km, and the layer of 4 -5kin depth is an apparent earthquake absence layer. The cross-section along the fracture＇s long axis shows there is an irregular seismic gap in the middle segment of the aftershock region, which is the rupture region of 3 the M6 3/4earthquake in 1955, and this earthquake occurred in the south of the gap. We believe that the Panzhihua Ms6. 1 earthquake sequence on August 30, 2008 was a result of rupture of the residual asperity caused by the stress adjustment of the Wenchuan Ms8. 0 earthquake. The other two profiles perpendicular to the long axis show that the focal depth in the north segment is larger and the fault plane dips NW, which is consistent with the dip of the Hongge fault.
