Eastern Tibetan Plateau deformation and its dynamimcs from Sentinel-1 InSAR and GPS data with a profile over 1000-km scale

Abstract:

Eastern Tibetan Plateau (ETP) plays a crucial role in Tibet dynamics. It is still in hot debate on how the crustal deforms after collision. Many competing models are proposed, such as the eastern extrusion of crustal materials (e.g., Hubbard and Shaw, 2009), channel flow (Clark and Royden, 2000) models etc. The GPS networks were developed in past few decades, providing an overall view of the plateau motion (Wang and Shen, 2020). InSAR data collected by old sensors provides localized deformation of particular faults, such as the Haiyuan fault (Cavalié et al.,2008) and the Xianshuihe fault (Wang et al., 2009) etc. However, we still need high-resolution deformation constraints on both fault-scale and continental scales. The systematically acquired Sentinel-1 radar data, particular the ETP, provide a unique source for this.

We processed the Sentinel-1 data accumulated in the past 5 years to study the deformation of the ETP in full resolution with point-like scatterers to resolve the interseismic deformation along a profile >1000 km long. We use multiple techniques to eliminate various noise terms (such APS, DEM and orbital errors etc.) to refine our solution. We also processed multiple overlapping ascending data to better characterize the deformation features. A method developed by Shen and Liu (2020) is used to further constrain the surface deformation in 3D by combing GPS data.

The profile covers all of the major faults in ETP, such as the Haiyuan, Western Qinlin, Kunlun, Longriba and Xianshuihe faults etc. The two creeping sections along the Haiyuan and the Xianshuihe fault are clear in our profile, indicating reliability of our solution. Besides, we find prominent left-lateral shear across the Kunlun fault at around N34. The Haiyuan creeping section shows a minor geometric change at very shallow depth, and the deeper parts seems still locking with relatively fast slip rate. This contrasts to the Xianshuihe fault, where creeping occur both at shallower and deeper parts. In all, we infer that the ETP is mostly experiencing extrusion, especially across the Kunlun fault. The long profile gives us good constraints on the ETP dynamics though without detailed geophysical observations. We are thriving to derive an even longer profile over 2000 km long to better constrain the material outflow at the ETP.