Abstract
Abstract. Three-dimensional (3-D) deformation fields with respect to the October 2016’s Central Tottori earthquake are extracted in this paper from ALOS-2 conducted Interferometric Synthetic Aperture Radar (InSAR) observations with four different incline angles, i.e., ascending/descending and left-/right-looking. In particular, the Strain Model and Variance Component Estimation (SM-VCE) method is developed to integrate the heterogeneous InSAR observations without being affected by the coverage inconformity of SAR images associated with the earthquake focal area. Compare with classical weighted least squares (WLS) method, SM-VCE method is capable for the retrieval of more accurate and complete deformation field of Central Tottori earthquake, as indicated by the comparison with the GNSS observations. In addition, accuracies of heterogeneous InSAR observations and 3-D deformations on each point are quantitatively provided by the SM-VCE method.
Highlights
Differential Interferometric Synthetic Aperture Radar (SAR, InSAR, DInSAR) has been proved a promising geodetic tool, mainly featured by its spatially high density of measurements, large scale of spatial coverage and high measurement accuracy, in monitoring the regional ground deformation associated with geological events such as earthquakes, volcanos, landslides, ice flows and land subsidence (Fialko et al, 2005; Hamling et al, 2017; J. Hu et al, 2014a; Jung et al, 2011)
The left-looking mode of SAR satellites is available as well, which is accompanied with notably different geometry in the process of imaging compare to the right-looking mode, making it possible that generating full 3D surface deformation maps, from only ascending and descending DInSAR measurements associated with the study zone (Yu et al, 2016)
A complete 3-D deformations field is derived from only DInSAR measurements with four distinct viewing angles (i.e., ascending left-looking (AsL), ascending right-looking (AsR), descending left-looking (DesL) and descending right-looking (DesR)) based on the recently proposed innovative method Strain Model and Variance Component Estimation (SM-Variance Component Estimation (VCE))
Summary
Differential Interferometric Synthetic Aperture Radar (SAR, InSAR, DInSAR) has been proved a promising geodetic tool, mainly featured by its spatially high density of measurements, large scale of spatial coverage and high measurement accuracy, in monitoring the regional ground deformation associated with geological events such as earthquakes, volcanos, landslides, ice flows and land subsidence (Fialko et al, 2005; Hamling et al, 2017; J. Hu et al, 2014a; Jung et al, 2011). The Pixel Offset-Tracking (POT) and/or Multi-Aperture InSAR (MAI) techniques, featured by ungraded accuracy but providing the complementary azimuth (AZI) direction deformation compare to DInSAR, are introduced to obtain 3-D surface deformations triggered by geophysical dynamics (e.g., earthquakes, volcanos), based on both ascending and descending SAR images (Jung et al, 2011; Michel et al, 1999). The left-looking mode of SAR satellites is available as well, which is accompanied with notably different geometry in the process of imaging compare to the right-looking mode, making it possible that generating full 3D surface deformation maps, from only ascending and descending DInSAR measurements associated with the study zone (Yu et al, 2016). For precise 3D deformations retrieval, a method named as SM-VCE (Strain Model and Variance Component Estimation), which considers both 3-D deformations relationship between adjacent points and weighting factors of each kind of measurements (Liu et al, 2018), is presented
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