PRESENT-DAY DEFORMATION ACROSS THE HAIYUAN FAULT (GANSU, CHINA), MEASURED BY SAR INTERFEROMETRY

摘要

The Haiyuan fault is a major left-lateral fault located atrnthe northeastern rim of Tibet. We use ERS InSAR datarncovering two adjacent tracks across its central segmentrn(the "Tianzhu seismic gap") to characterize its mechanicalrnbehavior for the period 1993-1998. Interferogramsrnare corrected for orbital and tropospheric errors, then selectedrnfor stacking depending on their signal to noise ratios,rnto derive average velocity maps for both independentrntracks. A steep velocity gradient is observed acrossrnthe fault, consistent with a left-lateral slip at a rate of 6.3rn±2 mm/yr below a locking depth of about 1.7 km. Suchrna small apparent locking depth may be indicative of transientrnsuperficial creep or related to a weak fault zone.