Crustal structure variations in northeast India from converted phases



[1] Teleseismic receiver functions from a ten station network deployed in northeast India region sampling the Shillong plateau, Mikir Hills, Himalayan foredeep and the Himalayan convergence zone, are analyzed to obtain the crustal structure in this seismically active but less studied region. The Shillong plateau and Mikir hills, away from the convergent margins, reveal remarkably simple crust with thickness (∼35 km) and Poisson's ratio (∼0.25), akin to the Indian shield values. A surprisingly thin crust for the uplifted Shillong plateau may be explained invoking presence of an uncompensated crust that popped up in response to tectonic forces. In contrast, crustal signatures from Assam valley suggest a thicker crust and higher Poisson's ratio with evidences for a dipping Moho. Predictably, the crust is much thicker and complicated in the eastern Himalaya further north, with values in excess of 50 km.