Abstract: Cross-fault deformation measurements have made an important contribution to the search for earthquake precursor information and strong earthquake prediction and forecasting efforts. Before the 2022 Qinghai Menyuan M6.9 earthquake, the cross-fault data in the Qilianshan-Haiyuan fault zone occured significant precursory anomalies. Based on the cross-fault data before earthquake, this paper uses time-series analysis, deformation anomaly intensity analysis, vertical deformation accumulation rate analysis and other methods to extract the temporal and spatial evolution characteristics of pre-earthquake anomalies, and analyse the short-term and medium-term fault activity and deformation mechanism before the earthquake. The results show that under the dynamic background of the combined action of NE-trending extrusion and NW-trending horizontal shear, the accumulation of deformation trend in the near-seismic region and its vicinity is at a high value, with a certain degree of strain accumulation background. Five years before the earthquake, the movement of the faults in the near-seismic area deviates from linearity and slows down. During the two years before the earthquake, the abnormal spatial distribution has the characteristics of migration and concentration to the epicentral area, which indicates that the crustal stress is accumuleting rapidly and locally enhanced in the near-epicentre area. Within half a year before the earthquake, multiple sites in the region of 60~120 km from the epicenter exhibited consistent tensional anomalies that were opposite to the compressional background, implying that micro-dynamic adjustment occurred after the stress in the near-seismic area accumulated to a certain extent, and pre-slip behaviors occurred.

Key words: Menyuan M6.9 earthquake, Cross-fault deformation, Abnormal features, Fault activity, Deformation mechanism