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CASE - Central Asia Structure and Evolution
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Tien Shan is the world largest and most active intracontinental mountain belt. The high level of historical and instrumental seismicity implies that crustal deformation in the Tien Shan is rapid. These mountain building processes result from a fast active convergence between India and Eurasia, with the Tien Shan absorbing almost half. This situation is absolutely unique for intracontinental mountain belts. The lithospheric mechanism controlling the crustal shortening remains remain however unresolved. A striking disagreement exists between the shortening rates of ~20 mm/yr (from GPS measurements) and ~10 mm/yr (from seismic moments of large crustal earthquakes). Density heterogeneity of the lithosphere and upper mantle is one of the main factors controlling tectonic processes. In the proposed study, we integrate gravity data from the new satellite missions CHAMP and GRACE, regional GPS observations, InSAR derived deformation results, new seismic data and tectonics to model density structure of the crust and upper mantle and to identify the style and intensity of the geodynamic processes responsible for high rate deformations in the region. In particular, the proposed study intends to provide constraints on the regional stress distribution, which control to a large extent seismicity in this highly populated region.