Abstract: Static stress change has been widely used since the concept of earthquake triggering was proposed. Corresponding effect of Coulomb failure stress of major earthquake and its aftershocks is influenced by many factors. Among them, fault slips at different depths lead to differences of the static Coulomb stress image at depth. To select the stress image at what depth to discuss the trend of subsequent earthquakes is an important issue. This paper presents a calculation method: Firstly, we calculate static Coulomb stresses at various depths, and then take the highest stress value at different depths at the same location to draw the static stress image. We take the 2010 Yushu earthquake for an example to assess the effect of the calculation method proposed in this paper combined with the seismic activity and the static Coulomb stress distribution. The results show that, in the two years after Yushu earthquake, the aftershock with magnitude larger than 3.0 occurred almost always in the Coulomb stress increase area, using two rupture models given by different researchers.

Key words: Coulomb stress, Earthquake triggering, Aftershocks, the 2010 Yushu earthquake