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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS014 Poster presentation 2318
Origin of tectonic stresses in the chinese continent and adjacent areas
Dr. Shoubiao Zhu
Geophysics Institute of Crustal Dynamics, CEA IASPEI
Yaolin Shi
Based on data of principal stress orientation from focal mechanism and of geological features in China,
we made pseudo-3D genetic algorithm finite element (GA-FEM) inversion to investigate the main forces
acting on the Chinese continent and adjacent areas which form the Chinese tectonic stress field. The
results confirm that plate boundary forces play the dominant role in forming the stress field in China, as
noticed by many previous researchers. However, we also find that topographic spreading forces, as well
as basal drag forces of the lower crust to the upper crust, make significant contribution to stresses in
regional scale. Forces acting on the Chinese continent can be outlined as follows: the collision of the
India plate to the NNE is the most important action, whereby forces oriented to the NW by the
Philippine plate and forces oriented to the SWW by the Pacific plate are also important. Topographic
spreading forces are not negligible at high topographic gradient zones, these forces are perpendicular to
edges of the Tibetan Plateau and a topographic gradient belt running in the NNE direction across
Eastern China. Basal drag forces applied by the ductile flow of the lower crust to the base of upper crust
affect the regional stress field in the Tibetan Plateau remarkably, producing the clockwise rotation
around the eastern Himalaya syntax.
Keywords: finite element, genetic algorithm, chinese continent