Abstract:

As the largest and most active extension fault in the southeast of the Qinghai-Tibet Plateau since Cenozoic Era, the Yadong-Gulu faults play an important role in regulating and transferring the tectonic deformation and material migration in the Qinghai-Tibet Plateau. However, due to the lack of geodetic observations, the estimates on the overall motion characteristics of the Yadong-Gulu fault is insufficient. Therefore, in this paper, we collected and processed the Sentinel data from October 2017 to April 2022 around the Yadong-Gulu fault, combined with the GNSS data to estimate and merge the crustal deformation in the different reference frames, and obtained the high-precision and resolution interseismic deformation covering the entire Yadong-Gulu fault region. Based on the elastic micro-block model, the present activity characteristics of the Yadong-Gulu fault are determined: the fault mainly dips to the east, with an optimum dip angle of 68°. The extensional slip rate is close to 2～6 mm/a, and gradually increases from south to north. In addition, the locking depth of the middle and north segments of the fault is about 14 km. However, the southern segment may be affected by the main Himalayan thrust, resulting in a shallow locking area (only 4 km). Finally, based on the slip deficit rate on the fault and the historical earthquakes, we infer that the future earthquake risk is higher in the northern segment, which provides an important reference for the regional geological hazard assessment.

Key words: Yadong-Gulu faults, GNSS, InSAR, extension rate, locking depth