The Tuotegongbaizi-Aerpaleike fault is located in the epicentral area of the 1902 Artux,Xinjiang earthquake of M S 81/4. It is a gently dipping reverse fault, merging downward into the decollement of South Tianshan Foreland Thrust belt at about 3km depth below the Earth surface. To the north of the epicentral area, lies the Muziduke thin-skinned arcuate nappe of the South Tianshan Foreland Thrust belt, while to the south lies the Mushi-Kashi-Artux arcuate recoil fold-thrust belt of northwest Tarim. The epicentral area is just located at the triangle zone of frontal structure of the juncture between these two major tectonic units. In the epicentral area a deep fault exists under the decollement of the thin-skinned nappe, extending downward to the Moho. It is located at the sharp gradient zone of the crust-mantle boundary between the South Tianshan and the Tarim basin. The projection of epicenter falls at a zone of abrupt change of crustal thickness. It seems that this great earthquake was the result of rapid faulting at the gradient zone of the crust-mantle boundary due to the action of N-S trending regional tectonic stress field. Because the focal depth is great, no earthquake faulting is observed on the surface. The deformation of the magistoseismic area is characterized mainly by physicogeologic phenomena such as collapse, landslides, and ground-fissures, accompanied by coseismic ruptures and folding of the active thin-skinned structures above the decollement.

This paper summarizes the basic characteristics of the arcuate structures in northeast Pamir, and analyzes the relationship between the E-W-trending thrust-anticline belts and the NNW-trending buried strike slip faults in northwest Tarim basin. In the northwest of Tarim Basin lie two thrust fault-anticline belts, which are called the Artush-Talanghe and the Kashi-Mingyaole anticline belts, respectively. Even though these two anticline belts are located far away from Pamir but closer to southwest Tianshan, their geometries and histories are similar to those of the external Pamir arcuate structures. By comparing the structures of the anticlines in Tarim basin with those of the southwest Tianshan and northeast Pamir, we find that these arcuate structures are propagating northeastward from Pamir toward the Tarim basin. The deformation in the area between the Pamir and southwest Tianshan is the result of the India-Eurasia collision. The northward indentation of the west Himalayan syntaxis has induced the development of the arcuate structures in Pamir and its fore deep depression basin. The stiff basement of the Tarim basin has also controlled the propagation of deformation. It transferred the tectonic force from Pamir to the area between its north margin and Tian Shan, resulting in intensive deformation of the area. The arcuate structures of the cover layers are thin-skinned structures resulted from crustal shortening of the Tarim basin. The focal depth and geophysical sounding data indicate that the basement of Tarim basin is under-thrusting beneath the south Pamir and south Tianshan. This movement has given rise to the propagation of deformation from the margin toward the inland of the basin. As the deformation is constrained by the orientation of tectonic force, the style of deformation in northwest Tarim basin is therefore similar to that in northeast Pamir. The NNW-trending strike slip faults in the northeast Pamir have also propagated eastward toward the Tarim basin. Most of the faults are buried, along which some strong earthquakes had occurred. It is more likely that these faults were developed in the basement of the Tarim basin. Along with the E-W-trending thrust faults, these strike slip faults have dissected the Tarim basin into several rhombic blocks, the north margins of which is dominated by compressive deformations while the east margin by dextral shearing deformations. Both the north and east margins of the block are seismogenic tectonics. The Jiashi strong earthquake swarms of 1997 and 1998 would be the result of the present-day movement of the arcuate structures in northwest Tarim basin.

Formed in Mesozoic-Cenozoic time, the Kuche depression on the south side of Tianshan and the Urumqi depression on the north side of Tianshan demonstrate striking similarities in geometry, kinematics and dynamics. However, the seismic activities, especially middle and large earthquakes show evident differences between the two depressions. This paper analyses the primary factors that cause the differences. They include: 1. the difference in deformation extent between the two depressions; 2. the difference in fine structure of gophysics between the two depressions; 3. the difference in the environment of geodynamics between the two depressions.