Abstract:Along the northeastern margin of the Tibetan Plateau, which is located at the intersection of the Tibetan Plateau, the Ordos, and the Alxa Block, a group of arc-shaped faults characterized by reverse strike-slip and strong new activity are developed. With frequent historical and modern strong earthquakes, the northeastern margin of the Tibetan Plateau is an ideal area for discussing the relationship between modern small earthquake-intensive areas and historical strong earthquakes. In this paper, based on the seismic instrument monitoring catalog of the study area since 1970, 21 earthquake intensive areas are divided by using the calculation method of density at grid nodes. Through the analysis of time distribution characteristics of small earthquake activities in each earthquake intensive area and previous research results of historical earthquakes and active faults, the corresponding relationship between earthquake intensive area and historical strong earthquake is comprehensively judged, and the duration of historical strong earthquake intensive area with different magnitudes are summarized. Meanwhile, this paper also presents the limited conditions for using the calculation method of density at grid nodes to check the historical earthquakes in the northeastern Tibetan Plateau. The results show that about 66.7% of the earthquake-intensive areas in the study area correspond to historical strong earthquakes, and there is a close correlation between them; The larger the magnitude of the earthquake, the longer the duration of the concentrated area. The fitting relationship between them is: T=4.38×10-7×M10.91.