2014年云南景谷M_s6.6地震序列重定位与震源机制解特征

Double Difference Relocation and Focal Mechanisms of the Jinggu M_s6.6 Earthquake Sequences in Yunnan Province in 2014

针对云南景谷地震序列的特征研究尚浅.为讨论2014年10月7日云南景谷Ms6.6地震的发震构造及序列分布,利用云南测震台网提供的波形数据及观测报告,采用MSDP软件中的Loc3dSB(川滇)模型对主震进行了精确定位,然后利用双差定位法对2014年10月7日至31日期间的余震序列进行了重新定位;并使用P波初动与振幅比联合反演方法计算了震源机制解.结果显示:序列以走滑型地震为主,主压应力具有北北东及北东两个优势方向,序列分布呈北西向线性展布,主体分布在西北端较浅而东南端较深的线性区域内,说明地震的初始破裂面可能为北西向节面,为一次右旋走滑地震;余震分布还具有清晰的端点及转换区域,存在显著的分段差异.另外,东南端的余震在晚期逐渐转移到几何形态明显不同的段落上,近期地震危险性值得关注.

The research of Yunnan Jinggu earthquake is not so intensive To discuss the seismogenic structure and distribution of se- quences of Jinggu Ms6.6 earthquake, 7 October 2014, we relocated the mainshock by using the 3D velocity model of Ytmnan and Sichuan province （Loc3dSB）, and then relocated the sequences during 7th to 31th October 2014 using the double-difference relocation algorithm, by using and phase data from seismic network of Yunnan province. Furthermore the focal mechanism solntions are derived by using P-wave polarity first-motion and amplitude ratio method. The sequences appear to be strike-slip type mostly, with the princi- pal compressive stress axis trends both NNE and NE directions. And the sequences are distributed dominantly linearly shaped in the NW direction with its southeast endpoint appears deeper than northwest. Both of which indicate that the early major rupture plane is the NW nodal plan, appears to be a right-lateral strike-slip faulting with a small normal component. Meanwhile the linearly shaped distribu- tion and focal mechanisms varies with locations on different segments, with clear end-points and transform segment. Furthermore, af- tershocks at SE end-point expand gradually to new geometrically unclear segment, which may indicate another rupture.