Interseismic slip rate of the Garze-Yushu fault belt in the Tibetan Plateau from C-band InSAR observations between 2003 and 2010

摘要

InSAR time series techniques can provide high-spatial resolution deformation fields across an active fault belt, even for zones with heavy vegetation coverage. An interseismic deformation map across the Garze-Yushu fault belt in the Tibetan Plateau, ~300 km by ~100 km, is derived from C-band Envisat/ASAR imagery collected between 2003 and 2010. Unlike previous research, we obtain a lookup figure which relates the slip rate with the fault locking depth, the dip angle and the rake angle. The estimated slip rate changes significantly with the locking depth and the rake angle, but relatively little with the dip angle. When considering the focal mechanism solutions of historical earthquake along the Garze-Yushu fault, the interseismic slip rate of the Garze-Yushu fault is close to a value of 6.4mm/yr, which is between the highest (18.2mm/yr) and the lowest (3.1 mm/yr) slip rate from GPS estimations, but slightly less than the minimum value (~ 7 mm/yr) from the geological estimations. The earthquake recurrence interval on the Yushu part of Garze-Yushu fault equals 272 yr, and the April 14, 2010 Mw 6.9 earthquake has not completely released the accumulated strain energy between 1738 and 2010.