Evolution of the deformation and stress patterns of the East Asia continent under multi-driving force

The India plates continuous motion to the north, the convective removal to the thickening lithosphere caused by small-scale mantle convection and the effect of denudation on the uplifted plateau are regarded as main driving forces that make the patterns of stress field of East Asia continent at present time. The method of numerical simulation is used to study the deformation and the stress field of East Asia continent under different boundary conditions, different denudation coefficients and different rock mechanics parameters within a trapezoid geological frame. Comparing with the results obtained by modern space geodetic technique (such as GPS) the results derived from seismological data show that the predicted data by our model can fit them very well. The degree of the fitness in the west is better than that in the east. These results imply that the main driving force of the deformation and the stress patterns of the west part of East Asia continent may come from the collision and compression between the India and the Eurasia plates. The interaction to the Pacific and the Philippines plates in the east part need to be considered. It also shows that the convective removal to the thickening lithosphere caused by small-scale mantle convection and the effect of denudation cannot be negligible in the evolution of the stress patterns.

Structure and seasonal changes in atmospheric boundary layer on coast of the east Antarctic continent

The temperature, humidity, and vertical distribution of ozone in the Antarctic atmospheric boundary layer（ABL） and their seasonal changes are analyzed, by using the high-resolution profile data obtained during the International Polar Year 2008 to 2009 at Zhongshan Station, to further the understanding of the structure and processes of the ABL. The results show that the fre- quency of the convective boundary layer in the warm season accounts for 84% of its annual occurrence frequency. The frequency of the stable boundary layer in the cold season accounts for 71% of its annual occurrence frequency. A neutral boundary layer ap- pears rarely. The average altitude of the convective boundary layer determined by the parcel method is 600 m; this is 200 to 300 m higher than that over inland Antarctica. The average altitude of the top of the boundary layer determined by the potential tempera- ture gradient and humidity gradient is 1 200 m in the warm season and 1 500 m in the cold season. The vertical structures of ozone and specific humidity in the ABL exhibit obvious seasonal changes. The specific humidity is very high with greater vertical gradi- ent in the warm season and very low with a lesser gradient in the cold season under 2 000 m. The atmospheric ozone in the ABL is consumed by photochemical processes in the warm season, which results in a slight difference in altitude. The sub-highest ozone center is located in the boundary layer, indicating that the ozone transferred from the stratosphere to the troposphere reaches the low boundary layer during October and November in Antarctica.

Discussion on the Abnormally Low Active Fault Slip Rate of the M_S 8. 0 Wenchuan Earthquake

Based on the collection of active fault slip rate data of large intra-continental shallow thrust earthquakes occurring in the triangular seismic region of the East Asia continent,a preliminary analysis has been performed with results showing that the Wenchuan,Sichuan, China earthquake ( MS = 8.0) of May 12,2008 occurred on the Longmenshan Mountain active fault with an abnormally low slip rate.