Recent Uplift Characteristics of the Southeast Tibetan Plateau, an Analysis Based on Fluvial Indices

Abstract

The southeastern Tibetan Plateau (SETP) is well known for its large strike–slip faults with high slip rates and a high potential for seismic hazards. However, little is known about its thrust faults and associated seismic hazards, even though they can produce devastating earthquakes despite their relatively low slip rate. Here we investigated the thrust faults and the recent tectonic uplift pattern in the SETP on a regional scale by combining geomorphic analysis and geodetic data. We quantify the potential differential uplift in the SETP recorded in the long-term landscape evolution with geomorphic indices and compare them with differential uplift derived from decadal leveling data and millennial-scale fluvial terrace incision rates. The results show that the northwest of the SETP underwent higher uplift rates compared to its southeast areas, which is in agreement with the GPS-based leveling. Essentially, the geomorphic indices build two value ranges that are spatially clustered and separated by the Muli thrust fault system, a transverse fault system, which is orientated oblique/perpendicular to the large strike–slip fault. The geomorphic indices indicating rapid uplift rates spatially correspond with high rates derived from leveling data on the northwest side of the Muli thrust fault. The Muli thrust fault, therefore, acted as an important topographic and tectonic boundary absorbing partial southeast crustal movement. Hence, further detailed studies, such as seismological investigations, are suggested to be conducted on the Muli fault for seismic hazards evaluation.