Abstract
Sentinel-1 Terrain Observation by Progressive Scans (TOPS) data have been widely applied in earthquake studies due to their open-source policy, short revisit cycle and wide coverage. However, significant near-fault displacement gradients and the moderate azimuth resolution of TOPS data make achieving high-precision along-track measurements challenging, which prevents the generation of high-quality three-dimensional (3D) displacement maps. Here, we propose an integrated method to retrieve high-quality 3D displacements based on the differential interferometric SAR (DInSAR), burst-overlap interferometry (BOI), multiple-aperture InSAR (MAI) and pixel offset tracking (POT) techniques, which are achieved to use only two track Sentinel-1 TOPS data with different viewing geometries. The key step of this method is using a weighted fusion algorithm with the interpolated BOI-derived and MAI-derived 3D displacements. In a case study of the 2021 Maduo earthquake, the calculated root mean square errors (RMSEs) from global navigation satellite system (GNSS) data and the InSAR-derived 3D displacement fields were found to be 6.3, 5.8 and 1.7 cm in north–south, east–west and up–down components, respectively. Moreover, the slip model of the 2021 Maduo earthquake jointly estimated by DInSAR and BOI measurements indicates that this seismic event was dominated by sinistral strike-slip motion mixed with some dip-slip movements; the estimated seismic moment was 1.75 × 1020 Nm, corresponding to a Mw 7.44 event.
Highlights
Since the Sentinel-1A and Sentinel-1B satellites launched on 3 April 2014 and 16 April2016, respectively
It is clear that the across-track displacements measured with the differential interferometric synthetic aperture radar (DInSAR) and pixel offset tracking (POT) methods were consistent with each other along the AA0 profile, but the range offsets contain more noise
The alongtrack displacements obtained with the multiple-aperture InSAR (MAI), burst-overlap interferometry (BOI) and POT approaches (Figure 4c,d) present significant differences, though the curve trends remained consistent along with the BB0 and
Summary
Since the Sentinel-1A and Sentinel-1B satellites launched on 3 April 2014 and 16 April2016, respectively. Sentinel-1 Terrain Observation by Progressive Scans (TOPS) data have been widely applied in geophysics, especially for monitoring crustal movements due to their advantages of short revisit cycle, wide coverage and free availability [1,2,3]. Traditional differential interferometric synthetic aperture radar (DInSAR) only allows for one-dimensional (1-D) displacement measurements in the light-of-sight (LOS) direction. InSAR data in near-fault zones may not be available due to the interferometric decorrelation likely caused by large displacement gradients. Due to polar-orbiting, the sensitivity of the north–south component of DInSAR measurements is the lowest compared to that of the other two components. It is impossible to retrieve the three-dimensional (3D) displacements based only on D-InSAR observation, even multi-track DInSAR measurements [4]
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