Abstract:In this paper, the anomalies of fault deformation before the Jan. 21th, 2016 Menyuan Ms6.4 earthquake, 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.
ZHANG Xi,JIA Peng,TANG Hongtao et al. Precursory Index Anomalies of Across-Fault Leveling before the Menyuan Ms6.4 Earthquake and the Variation after the Earthquake[J]. jgg, 2016, 36(4): 283-287.