Seismic Investigation of the Northern Tibetan Margin

Abstract

This report describes the dataset and some results from a deployment of both a linear array and an areal array in Northern Tibet. The experiment was a collaboration of German, US, British and Chinese universities and institutions, with stations provided by IRIS-PASSCAL, SeisUK and GIPP (GFZ-Pool). The northern edge of Tibet, where the Kunlun mountains drop towards the Qaidam basin is marked by a steep Moho step, shallowing from 70 km to 50 km Moho depth. The upper mantle below northern Tibet is characterised by an unusual doubled negative polarity discontinuity at 100 and 160 km depth (300 km). Lower velocities are found beneath the Kunlun mountains and Songpan-Ganzi terrane to large depths (300 km). Below the northern Tibetan plateau (Qiangtang terrane) the lower velocities imaged in previous studies are shown to only be present west of 94E. The data from the British stations of this network are archived at SeisUK and the IRIS-DMC with FDSN network code XO (valid for years 2007-08).