TECTONIC DEFORMATION OF THE TIBET PLATEUA AND THE WENCHUAN EARTHQUAKE REN Jinwei and Xiong Renwei

1. 2008Bilateral Workshop under the Sino - US Earthquake Studies Protocol TECTONIC DEFORMATIONOF THE TIBET PLATEUA AND THE WENCHUAN EARTHQUAKE REN Jinwei and Xiong Renwei Institute of Earthquake Science, CEA, Beijing 100036, China Email: ren@seis.ac.cn Sun Xiong and Song Xiaoming Earthquake Administration of Qinghai Province, Xi'nin 810001, China November 11-14, 2008 Boulder, Colorado, USA

2. Active Tectonics of Tibetan Plateau

3. Fault scarp in the Gulu Basin (Dangxiong graben)

4. Fault scarp in the Gulu Basin (Dangxiong graben)

5. Fault scarp in the Gulu Basin (Dangxiong graben)

6. Fault scarp in Wenquan (hot spring) basin

7. Linear tufa in Wenquan (hot spring) basin

8. A A’ 4200 4155 4143 4122 3996 A’ A Air photograph of Ranwu area, south-eastern Tibet 2.5km

10. North-western segment of Jiali fault

11. Landslides along the normal fault at Daren Basin

12. Scarps along the Jiali fault

13. T3 Fault scarp T2 T1 Fault scarp along the BNS (south of Tanggula)

14. In the southern part of the Tibetan plateau (Lhasa terrane and Bangong-Nujiang suture), the deformation is dominated by east-west extension • The deformation is occurred throughout the Lhasa terrane, along the suture the deformation is not significant • The strike slip motion of the faults in this area is most likely related to the extension

15. Active Tectonics of Tibetan Plateau

16. Thrust fault along the Jinsha Suture (south of Erdaogou)

17. Deformation of the alluvium south of Erdaogou

18. Along the Jinsha suture, neo-tectonic deformation is dominated by the thrust faulting and it mainly occurred along the suture • Within the Qiangtang terrane, the deformation is minor

19. Active Tectonics of Tibetan Plateau

20. The highway was offset 3m by the ruptures at Kunlun Pass

21. 5.8 m Surface Ruptures Left lateral displacement 90km west of Kunlun Pass

22. Surface ruptures along the Kunlun pass fault by 2001 earthquake

23. Active Tectonics of Tibetan Plateau

24. Surface ruptures along the east Kunlun fault by 1937 earthquake

25. Surface ruptures along the east Kunlun fault by 1937 earthquake

26. Surface ruptures along the east Kunlun fault by 1937 earthquake

27. Surface ruptures along the east Kunlun fault by 1937 earthquake

28. Active Tectonics of Tibetan Plateau

29. Surface ruptures along the east Kunlun fault near Maqin

30. Surface ruptures along the east Kunlun fault eastof Maqin

31. Surface ruptures along the east Kunlun fault east Maqin

32. Surface ruptures along the east Kunlun fault near Maqin

33. Along the Kunlun suture, neo-tectonic deformation is dominated by left lateral strike slip faulting and it mainly occurred along the suture • large earthquakes occurred along the east Kunlun fault in the last century, the surface ruptures caused by these events had almost gone through the entire fault

34. Crust Movement of China Continent GPS Data from CMONOC

36. Fold caused by the strike slip motion by 2001 earthquake

37. Large Earthquakes along the Kunlun Fault 2001/8.1 1963/7.0 ????/>7.5 1937/7.5 1947/7.5

38. CONCLUSION REMARKS • The crust deformation of the Tibetan plateau is dominated by east-west extension in the southern part and the material in northern part of the plateau has been penetrated eastward. • The eastward flow is separated by several large left-lateral strike-slip faults. Once the movement of the blocks between the faults are obstructed, thrust faults would be created to accommodate the deformation transfered by the strike slip faults. Longmenshan fault on which the Wenchuan earthquake occurred, is one of the thrust fault that accommodate the deformation transfered by the East Kunlun fault. • Along the East Kunlun fault there were several large earthquakes occurred in last century. Field investigation shows that the surface ruptures created by these large earthquakes have gone through the whole East Kunlun fault, which means that the East Knulun fault could not hold up the deformation any longer, and all the burden were transfered to Longmenshan fault. This might be the reason of the occurrence of Wenchuan earthquake. November 11-14, 2008 Boulder, Colorado, USA

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41. 东大滩谷地北侧发育的叠瓦状构造