Geodetic evidence for a low slip rate in the Altyn Tagh fault system

Abstract

The collision between India and Asia has been simulated with a variety of computational models that describe or predict the motions of the main faults of east Asia. Geological slip-rate estimates of 20–30 mm yr ^-1 suggest that the largest of these faults, the 2,000-km-long Altyn Tagh fault system on the northern edge of the Tibetan plateau, absorbs as much of the Indo-Asian convergence signal as do the Himalayas^1,2—partly by oblique slip and partly by contraction and mountain growth^3,4,5. However, the predictions of dynamic models for Asian deformation⁶ and the lower bounds of some geological slip-rates estimates (3–9 mm yr ^-1; refs 7, 8) suggest that the Altyn Tagh system is less active. Here, we report geodetic data from 89–91° E that indicate left-lateral shear of 9 ± 5 mm yr^-1 and contraction of 3 ± 1 mm yr^-1 across the Altyn Tagh system. This result—combined with our finding that, at 90° E, Tibet contracts north–south at 9 ± 1 mm yr^-1—supports the predictions of dynamic models of Asian deformation.