Abstract: There are 6 M>7.0 earthquakes successively occurred in the west of China and nearby regions since 1900. They are located near the 35°N line, and their latitudes range between 34.4°~36.2°N with the average of 35.45°N. According to focal mechanisms given by Harvard University, the azimuths of these earthquake's compression stress axes are almost along the direction of northeast. This paper shows that these earthquake's occurrences could result from the unified stress field possibly related to the push of the Indian plate to mainland China. We determined their seismic source faults by tectonic fault and the special distribution of the aftershocks, and calculated the stress fields caused by the earthquakes. According to the change of the Coulomb failure stress, we analyzed the interactions of them. The result shows that these s, the former earthquake have triggering effects on subsequent earthquake. According to the effective shear stress on the focal fault plane caused by the earth tide, the triggering effect of the earth tide for these earthquakes is analyzed, the result does not demonstrate that these earthquakes are triggered by earth tide.

Key words: West of mainland China, the 35°N Line, Activity of Strong Earthquakes, Interaction