川滇菱形块体东边界地震精定位

选用四川及云南地震台站资料,采用多阶段地震定位法(Hypo2000+Velest+HypoDD),对四川境内川滇菱形块体东边界的道孚南至巧家段2010年1月1日~2014年12月31日7787次地震进行了精定位。精定位后,震源位置精度明显提高,震中分布与地震断裂带线性展布较一致。定位结果显示,鲜水河断裂带东南段地震分布相对密集,鲜水河南段与安宁河断裂带、小金河断裂带及以东的大凉山断裂带交叉区域相对密集。深度剖面图沿活动断裂带地震活动分段活动特征明显,横跨鲜水河、安宁河和大凉山等断裂的剖面呈现出石棉附近多断裂交汇处的断层间复杂的相互作用,地震明显分为深、浅两丛。15~20km深度范围地震非常稀少,这与朱艾斓提出的14~19km塑性流变的层厚和位置较一致。

Precise Location of Earthquakes at the Eastern Boundaries of Diamond Block of Sichuan-Yunnan

Based on seismic station dataset of Sichuan and Yunnan Provinces,we performed a multi-stage seismic location method(Hypo 2000+Velest+HypoDD)to precisely locate 7787 earthquakes taking place during 2010~2015 along the eastern boundaries of the diamond block of Sichuan-Yunnan,namely from the southern Dawu to Qiaojia segment. The final results show the location precision is advanced greatly and the epicenter distribution exhibits a good consistency with the linear distribution of the seismic faults. The earthquake distribution is quite intensive at the intersection region among the southern segment of the Xianshuihe fault,the Anninghe fault zone,the Xiaojinhe fault zone and the Daliang Mountain fault zone to the east. The depth profile of seismicity shows a clear stepwise activity along the active seismic fault zones. The profile that crosses the faults of the Xinshuihe,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. The earthquake is very rare at the depth of 15~20km,which is consistent with the region of the plastic rheology between 14~19km calculated by Zhu Ailan.