G024-04
A high-resolution crustal velocity field for the Alpine-Himalayan Seismic Belt from Sentinel-1 InSAR and GNSS
Wednesday, 16 December 2020: 19:12
Virtual
Tim J Wright1, Chris Rollins1, Yasser Maghsoudi2, Milan Lazecky1, Yu Morishita3, Simon Daout4, John R Elliott2, Andrew J Hooper2, Qi Ou4, Barry Parsons4, Lin Shen1, Andrew Watson1 and Jonathan R. Weiss5, (1)University of Leeds, COMET, School of Earth and Environment, Leeds, LS2, United Kingdom, (2)University of Leeds, COMET, School of Earth and Environment, Leeds, United Kingdom, (3)Geography and Crustal Dynamics Research Center, Geospatial Information Authority of Japan, Tsukuba, Japan, (4)University of Oxford, COMET, Department of Earth Sciences, Oxford, United Kingdom, (5)University of Potsdam, Institute of Geosciences, Potsdam, Germany
Abstract:
Accurate measurements of surface deformation are key observations for understanding geodynamics and hazards. GNSS data provide accurate 3D velocities at individual points, but in many parts of the world are too sparse to enable us to discriminate key processes, such as the extent to which crustal faults are locked or creeping, or whether localised deformation exists around magmatic centres. InSAR data can be used to provide 1D measurements of surface deformation, but extracting accurate crustal velocities requires processing of massive volumes of data acquired over extended time periods. The launch of Copernicus Sentinel-1A in 2014 and Sentinel-1B in 2016 have provided the most comprehensive set of radar acquisitions to date for the seismic belts. In COMET, the UK’s Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics, we have built the LiCSAR system (Lazecky et al., 2020) to automatically process interferograms from Sentinel-1 data over tectonic and volcanic areas. Processed data are made freely available to the community (
https://comet.nerc.ac.uk/comet-lics-portal/.)
Here we present a high-resolution crustal velocity field for the Alpine-Himalayan Seismic Belt (AHSB) derived by combining Sentinel-1 InSAR and GNSS. We use a modified NSBAS approach (LiCSBAS; Morishita et al., 2020) to create time series and average velocities from ~300,000 interferograms that cover 575 frames, each ~220 by 250 km, with an average of 170 acquisitions per frame. We tie the velocities to a Eurasian reference frame by jointly inverting the InSAR data with GNSS data from the Global Strain Rate Model to produce a low-resolution model of 3D surface velocities that fits both data sets. We use the referenced InSAR velocities to invert for east-west and sub-vertical velocity fields at 1 km resolution for the entire region, the latter being a weighted combination of vertical and north-south velocities. Vertical velocities are dominated by non-tectonic deformation, such as water extraction. The horizontal velocity field reveals the tectonics of the AHSB with unprecedented sharpness. We discuss the implications for our understanding of faulting and continental tectonics.
Lazecky et al., 2020: https://doi.org/10.3390/rs12152430
Morishita et al., 2020: https://doi.org/10.3390/rs12030424
