Abstract: Based on across-fault short leveling data of the northeastern margin of Qinghai-Tibet Plateau, combined with calculation methods such as deformation anomaly intensity, deformation synthetic rate and deformation trend accumulation rate, and the adopted research thought of combining of point, line and area, we comprehensively analyzed strain background, fault activity and short-term deformation characteristics before the 2013 Minxian-Zhangxian M6.6 earthquake. The results show that: ① This earthquake occurred in the period of the vertical deformation rate at a high value and high degree of strain accumulation; ② The medium-term movement rate significantly increased in the seismogenic fault and there was a significant differential movement between the faults, which caused regional imbalance of motion and strain accumulation of western Qinling area; ③ With the approximation of earthquake, significant anomaly fields migrated and concentrated to the near-source area and abnormal level also increased. These results have short-term instruction for the prediction of earthquake’s location and occurrence time. In conclusion, the combination of point-line-area research method is beneficial to understand earthquake precursor information, and would be of importance in the judgment of seismogenic background and analysis of seismic hazard.

Key words: across-fault observation, Point-line-area analysis method, The 2013 Minxian-Zhangxian M6.6 earthquake