Deriving centimeter-level coseismic deformation and fault geometries of small-to-moderate earthquakes from time-series Sentinel-1 SAR images

Small-to-moderate earthquakes (e.g. ≤Mw5.5) occur much more frequently than large ones (e.g. >Mw6.0), yet are difficult to study with InSAR due to their weak surface deformation that are severely contaminated by atmospheric delays. Here we propose a stacking method using time-series SAR images that can effectively suppress atmospheric phase screens and extract weak coseismic deformation in centimeter to sub-centimeter level. Using this method, we successfully derive coseismic surface deformations for three small-to-moderate (Mw∼5) earthquakes in Tibet Plateau and Tienshan region from time-series Sentinel-1 SAR images, with peak line-of-sight deformation ranging from 5–6 mm to 13 mm. We also propose a strategy to downsample interferograms with weak deformation signal based on quadtree mesh obtained from preliminary slip model. With the downsampled datasets, we invert for the centroid locations, fault geometries and slips of these events. Our results demonstrate the potential of using time-series InSAR images to enrich earthquake catalog with geodetic observations for further study of earthquake cycle and active tectonics.Nanyang Technological UniversityPublished versionThis work was supported by the National Key Research and Development Program of China (Grant No. 2019YFC1509201) and the National Science Foundation of China (NSFC Grant Nos. U1939202 and 41974017). Shengji Wei is partially supported by Earth Observatory of Singapore grant 04MNS001909A620