Complete Three-Dimensional Coseismic Deformation Field of the 2016 Central Tottori Earthquake by Integrating Left- and Right-Looking InSAR Observations With the Improved SM-VCE Method

The three-dimensional (3-D) deformation field associated with the 2016 Central Tottori earthquake is retrieved from advanced land observing satellite 2 interferometric synthetic aperture radar (InSAR) observations with four different viewing geometries, that is, ascending/descending tracks and left-/right-looking modes. The strain model and variance component estimation (SM, VCE, SM-VCE) method is exploited and improved to integrate the InSAR observations with different viewing geometries so that the 3-D deformation field is not affected by the inconsistent coverage of SAR footprints or the gross errors in InSAR observations. The obtained results are consistent with GNSS observations, indicating that the improved SM-VCE method, known as SM-RVCE in this paper, is capable of retrieving an accurate and spatially complete 3-D deformation field for this earthquake. In addition, the precision of the InSAR observations and the estimated 3-D deformation are quantitatively assessed by the SM-RVCE method. Finally, on the basis of the estimated 3-D coseismic deformation, the source parameters of this event are inverted, revealing an asperity with a maximum strike-parallel slip of ~1.1 m concentrated at depths between 2 and 10 km. The estimated seismic moment is 2.4 × 10¹⁸ Nm, which corresponds to a Mw 6.2 event.