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Late Cenozoic tectonic stresses and focal mechanism of some of the largest earthquakes of the Tien-Shan region
- Almalyk Mining and Metallurgical Faculty, Navoi State Mining Institute, Almalyk, Uzbekistan
- Gubkin Russian State University of Oil and Gas, Tashkent branch, Tashkent, Uzbekistan
https://doi.org/10.1016/j.crte.2012.03.003
Highlights
- Regional stress: maximum compression oriented northwest, minimum compression (relative tension) northeast.
- Earthquakes studied: Suusamyr 1992 (M 7.3), Tavaksay 1977 (M 5.2), Karatag 1907 (M 7.0, 7.2, 7.3, 6.2).
- The Talas–Fergana shear zone shapes the stresses in the Suusamyrtau and Karzhantau areas.
- Gissar area: compression and tension domains alternate.
Keywords
- stress field
- Tien Shan
- fault kinematics and dynamics
- tectonics
- earthquake focal mechanisms
- seismogenic dislocations
Summary
The article summarises field studies of crack systems, of the kinematics and dynamics of fault zones and individual faults, and of fault-slip data from the epicentral zones of the strong Suusamyr (1992, M = 7.3), Tavaksay (1977, M = 5.2) and Karatag (1907, M = 7.0, 7.2, 7.3 and 6.2) earthquakes. From the geological and structural data the author reconstructed the average and local directions of the tectonic stress axes and compiled the structural and dynamic pattern of the crustal blocks in the epicentral zones.
Across the whole area the regional stress field has its maximum compression axis oriented northwest and its minimum compression axis northeast, that is, relative tension. In the Suusamyrtau and Karzhantau areas, shear movements in opposite directions coexist under the same stress field, and the influence of the Talas–Fergana shear zone is clear. In the Gissar area, domains of compression and tension alternate. Stress diagrams from structural geology and from earthquake focal mechanisms are similar for the epicentral areas, so the mechanism of future earthquakes can be forecast from field data collected in tectonic studies of areas with seismic hazard.
How to cite
R. A. Umurzakov (2012). Late Cenozoic tectonic stresses and focal mechanism of some of the largest earthquakes of the Tien-Shan region. Comptes Rendus Geoscience, vol. 344, no. 3–4, pp. 239–246. https://doi.org/10.1016/j.crte.2012.03.003