TITLE:
Up-To-Date Geodynamics and Seismicity of Central Asia
AUTHORS:
Yury Gatinsky, Dmitry Rundquist, Galina Vladova, Tatiana Prokhorova
KEYWORDS:
Lithosphere Plates, Seismicity, Active Faults, Transit Zone, Interblock Zones, Seismic Energy
JOURNAL NAME:
International Journal of Geosciences,
Vol.2 No.1,
February
24,
2011
ABSTRACT: The analysis of the seismicity in central Asia shows its distribution within a “triangle” of maximal inner-continental seismic activity, which is situated between south edge of the Lake Baikal and the Himalayas. The “triangle” coincides with the central Asian transit zone which divides the north Eurasian and Indian lithosphere plates and provides transfer and relaxation of tectonic stresses that arise between them. The central Asian transit zone consists of numerous crust blocks of different sizes. Blocks’ boundaries are often represented by not only single faults but relatively wide interblock zones characterized by intensive shattering of rocks and releasing a significant quantity of the seismic energy. The most active interblock zones limited the Pamirs, Tien Shan, Shan, and Bayanhar blocks as well as north boundaries of the Indian Plate. The quantity of the seismic energy releasing along each of them reaches ≥ 5?1015 J, while along other boundaries it doesn’t exceed 3?1012-2?1015 J. The majority of the most intensive seismic events took place just in these interblock zones. The total quantity of seismic energy is generally diminished away from the boundary of the Indian Plate, but sometimes the maximal quantity releases in inner parts of the transit zone at the distance 500-1500 km from the plate boundary. The most active interblock zones of central Asia differ from subduction and collision zones by depth of their penetration in lithosphere and at the same time are rather near to them by the volume of energy realizing. The examination of interblock zones shows that the majority of intensives earthquakes occur within them in regions with sharp changes of geodynamic conditions. On the whole the most part of central Asia is situated under the influence of the Indian indenter, which causes the prevailing of transpression tectonics. An abnormal high seismic energy releasing depends of deep continuation of the plate slab in collision zones (Pamirs, Himalayas), intensive displacements along strike-slips and thrusts due to collision processes and deep lithosphere unhomogeneity (Tien Shan, Bayanhar), as well as of sharp changes of geodynamic conditions because of influence of plate movement and supposed mantle plumes (north Mongolia, the Baikal region).