Abstract We calculate the lithospheric bottom mantle convection stress field of southeastern Tibetan plateau using 11~36 spherical harmonic coefficients of gravity model EGM2008. Meanwhile we collect and organize the focal mechanism of 1 131 earthquakes that occurred from 2000 to the present in southeastern Tibetan plateau. The current seismogenic layer stress and stress field before Lushan earthquake are calculated by the damping regional stress tensor inversion. We further analyze the correlation between the two kinds of stress fields, then discuss the relation between mechanics coupling situation and strong earthquakes in different regions. The results show that: (1) Most of southeastern Tibetan plateau is located in the coupling and decoupling intermediate zone. Coupling zones distribute on the basis of block; the eastern south China block has strong coupling, and the coupling phenomenon also exists in parts of the northern Tibet block, Bayan Har block in the northwest, and southwest Yunnan block. The decoupling mainly occurs in Songpan-Ganzi block, connecting with the strong coupling south China block and Longmenshan fault zone, which is their boundary. (2) We analyze the seismogenic mechanism, then propose that the border zone, of strong and weak coupling relation between mantle convection stress and seismogenic layer stress, presents a high seismic risk. The current coupling situation shows that Longmenshan fault zone is still in the large varying gradient area of coupling intensity level, and has conditions to accumulate energy and develop earthquakes. Other dangerous areas are: Mingjiang fault zone, Xianshuihe-Anninghe-Zemuhe fault zone, the Red river fault zone, Nantinghe fault zone and their neighboring areas.
HOU Qiang,YAO Yafeng,DING Xiaojun et al. Coupling Relationship between Mantle Convection and Seismic Stress Field in Southeastern Tibetan Plateau[J]. jgg, 2019, 39(9): 890-895.
HOU Qiang,YAO Yafeng,DING Xiaojun et al. Coupling Relationship between Mantle Convection and Seismic Stress Field in Southeastern Tibetan Plateau[J]. jgg, 2019, 39(9): 890-895.