Abstract:In order to extract the trend turning point of time series, we propose an improved algorithm based on the combination of vector turning angles and extreme points applied to the analysis of seismic observation data. Combined with the corresponding rules of earthquakes, we evaluate the seismic prediction effectiveness of the XM1-XM2 line of Xiaomo mobile leveling, located in the northern Shanxi fault depression. The results show that: 1) The algorithm can be used to automatically extract the trend turning points of the time series, improving the efficiency of manual discrimination, and achieving the quantitative identification of turning points; 2) From the perspective of data statistics, the XM1-XM2 line has a good corresponding relationship with M>4.5 earthquakes within 200 km. The evaluation result of prediction effectiveness is R=0.63(R0=0.43); 3) The seismic inflating rate of this line after 2000 is higher, probably related to the stress change caused by the far field effect from strong earthquake.