Abstract:For the purpose of rapid assessment of the direction of rupture faults in large earthquakes for the earthquake intensity report,we collected observational data from multiple earthquakes in western China,and used trend-surface analysis method to explore the directional difference characteristics of the initial P-wave parameters of the stations within a certain range of the epicenter based on the theory of limited moving sources. Then,we proposed a method for quickly assessing the direction of a seismic rupture fault by using initial P wave and trend-surface analysis. We also put forward a method for determining the fault rupture mode of the earthquake by calculating the optimal fitting parameters of least squares statistical regression by using the fault distance model. Through real earthquake cases,the consistency between the evaluation results of the proposed method and the actual fault rupture distribution is compared and analyzed,which proves the reliability and practicability of the method. The study provides a new idea for the rapid determination of earthquake fault rupture direction using real-time seismic monitoring stations,as well as a reference for the dynamic correction of the results of rapid earthquake intensity report.