Continental Dynamics in High Tibetan Plateau： Normal Faulting Type Earthquake Activities and Mechanisms

• Published in: Journal of earth science (Wuhan, China) Vol. 20; no. 2; pp. 484 - 492
• Main Author: 徐纪人 赵志新
• Format: Journal Article
• Language: English
• Published: China University of Geosciences (Wuhan) China University of Geosciences (Wuhan) 01-04-2009; Springer Nature B.V
• Subjects: Biogeosciences; Earth and Environmental Science; Earth science; Earth Sciences; Earthquakes; Fault lines; Geochemistry; Geology; Geotechnical Engineering & Applied Earth Sciences; Plate tectonics; Seismic activity; Seismology; Topography; 伸展运动; 地震活动; 大陆动力学; 正断层型地震; 生理盐水; 西藏高原; 青藏高原; eastward extensional motion; stress field; normal faulting type earthquake; focal mechanism solution; gravitational collapse
• ISSN: 1674-487X; 1867-111X
• DOI: 10.1007/s12583-009-0040-1

Various earthquake fault types were analyzed for this study on the crust movement in the high region of the Tibetan plateau by analyzing mechanism solutions and stress fields. The results show that a lot of normal faulting type earthquakes are concentrated in the central High Tibetan plateau. Many of them are nearly perfect normal fault events. The strikes of the fault planes of normal faulting earthquakes are almost in an N-S direction based on the analyses of the Wulff stereonet diagrams of fault plane solutions. It implies that the dislocation slip vectors of the normal faulting type events have quite great components in the E-W direction. The extensions probably are an eastward extensional mo- tion, being mainly a tectonic active regime in the plateau altitudes. The tensional stress in the E-W or NWW-SEE direction predominates earthquake occurrences in the normal event region of the central plateau. The eastward extensional motion in the high Tibetan plateau is attributable to the gravitational collapse of the high plateau and the eastward extrusion of hotter mantle materials beneath the east boundary of the plateau. Extensional motions from the relaxation of the topography and/or gravitational collapse in the high plateau hardly occurred along the N-S direction. The obstruction for the plateau to move eastward is rather weak.