Large-scale Interseismic Strain Mapping of the NE Tibetan Plateau from
Sentinel-1 Interferometry
Abstract
The launches of the Sentinel-1 synthetic aperture radar satellites in
2014 and 2016 started a new era of high-resolution velocity and strain
rate mapping for the continents. However, multiple challenges exist in
tying independently processed velocity data sets to a common reference
frame and producing high-resolution strain rate fields. We analyse
Sentinel-1 data acquired between 2014 and 2019 over the northeast
Tibetan Plateau, and develop new methods to derive east and vertical
velocities with ~100 m resolution and ~1
mm/yr accuracy across an area of 440,000 km^2. By implementing a new
method of combining horizontal gradients of filtered east and
interpolated north velocities, we derive the first ~1 km
resolution strain rate field for this tectonically active region. The
strain rate fields show concentrated shear strain along the Haiyuan and
East Kunlun Faults, and local contractional strain on fault junctions,
within the Qilianshan thrusts, and around the Longyangxia Reservoir. The
Laohushan-Jingtai creeping section of the Haiyuan Fault is highlighted
in our data set by extremely rapid strain rates. Strain across unknown
portions of the Haiyuan Fault system, including shear on the eastern
extension of the Dabanshan Fault and contraction at the western flank of
the Quwushan, highlight unmapped tectonic structures. In addition to the
uplift across most of the lowlands, the vertical velocities also contain
climatic, hydrological or anthropogenic-related deformation signals. We
demonstrate the enhanced view of large-scale active tectonic processes
provided by high-resolution velocities and strain rates derived from
Sentinel-1 data and highlight associated wide-ranging research
applications.