门源6.4级地震前跨断层水准前兆性指标异常与震后变化

Precursory Index Anomalies of Across-Fault Leveling before the Menyuan Ms6.4 Earthquake and the Variation after the Quake

利用2016-01-21门源6.4级地震前祁连山断裂带跨断层短水准观测资料以及震后数天的加密复测结果,综合观测曲线、异常时空演化特征及特征强度指标,分析门源震前断层形变异常及震后变化。结果显示,2015年该断裂带中东段集中、增多且以突跳为主的断层形变短期群体性异常与这次门源强震有一定关联,具有中短期-短期前兆意义;震后复测结果以转折特性为主,同震变形不是很大。

In this paper,the anomalies of fault deformation before the Jan.21 th,2016 Menyuan Ms6.4earthquake,and their variations after the quake,are synthetically analyzed.To do so,we use the data of across-fault short-leveling at the Qilian Mountain fracture zone,additional data observed in the several days after the quake,as well as the aid of observational curves and time-space evolution of the anomalies and the index of feature intensity.The results show that,in 2015,the group short-term anomalies of fault deformation appear in the middle-eastern segment of this fracture zone and display an obvious increasing trend,mainly revealing abrupt change characteristics.These anomalies are related to the Menyuan earthquake to some degree,which have medium-short-term or short-term precursory features.Moreover,observational data after the earthquake reveal the faults＇ deformations are mainly turning features,suggesting that the co-seismic deformations are not very significant.