Nailing down the slip rate of the Altyn Tagh fault

Abstract

Previous estimates of the geodetic and geologic slip rates of the 1500 km long Altyn Tagh fault bordering the northern edge of the Tibetan plateau vary by a factor of five. Proposed reasons for these discrepancies include poor GPS geometry, interpretative errors in terrace morphology, and changes in fault slip rate over time. Here we present results from a new dense GPS array orthogonal to the fault at ∼86.2°E that indicates a velocity of 9.0 -3.2/+4.4 mm/yr, in close agreement with geomorphologic estimates at the same location. Our estimated geodetic slip rate is consistent with recent geological slip rates based on terrace offsets. The resulting mean combined geological and geodetic slip rate (9.0 ± 4.0 mm/yr) is remarkably uniform for the central ∼800 km of the Altyn Tagh fault, significantly lower than early kinematic estimates and consistent with deformation elsewhere in Tibet and central Asia. Key Points Previously estimated slip rates of the ATF differ by a factor of five A new GPS profile shows that the geological and geodetic slip rates are comparable Along ∼1000 km length of the fault, the slip rate is uniform about 9 mm/yr ©2013. American Geophysical Union. All Rights Reserved.