9316358 Ni This is a project to deploy a passive-source broadband seismic array to complement the core reflection profiling experiment (INDEPTH II - a funded CD project) across the Tsangpo Suture in Tibet. The array will be equipped with 12 broadband seismometers contributed by the P.I.'s German colleagues, and will record for 8- 9 months beginning in May, 1994. Although the reflection profiling experiment is expected to image the top of the underthrusting Indian Plate, the behavior of the mantle part of the lithosphere is unknown. The anomalous velocity structure of the upper mantle beneath southern Tibet can be imaged by a passive-source PASSCAL-type experiment. The main objective of the proposed broadband study is to search for the mantle downwelling beneath southern Tibet. ***