Convergence across the northwest Himalaya from GPS measurements

Abstract

Horizontal velocities of 26 Global Positioning System (GPS) stations in the northwest Himalayan region provide new constraints on the partitioning of India-Eurasia convergence and elastic strain accumulation about the locked Main Frontal Thrust (MFT). The northwest-striking Karakorum fault slips at 11 ± 4 mm/yr and contributes to east-west extension of southern Tibet and westward motion of the northwest Himalaya towards Nanga Parbat, rather than playing a role in eastward extrusion of Tibet. Crustal shortening across the Himalaya occurs within a zone centered about 100 km north of the Siwalik Foothills and the MFT. Model inversions of the GPS data indicate that the MFT is locked over a width of ∼ 100 km. Comparison with geologic MFT-slip-rate estimates suggests that this zone is building up a slip deficit at a rate of 14 ± 1 mm/yr and will eventually fail in future great earthquakes.