[S-TT39] Synthetic Aperture Radar and its application

[STT39-09] Unwrapping dense and complex SAR interferograms: Examples from the 2023 Turkey Earthquake

*Yo Fukushima¹, Yagizalp Okur^2,3 (1.International Research Institute of Disaster Science, Tohoku University, 2.Graduate School of Science, Tohoku University, 3.Clermont-Auvergne University)

Keywords:InSAR, Turkey, Earthquake, Phase unwrapping

Interferometric SAR (InSAR) analysis outputs the displacements in the line-of-sight (LOS) component that occurred during two dates of acquisition. For significant events such as the earthquake occurred along the East Anatolian Fault in the southeastern Turkey in February 2023 (Mw 7.8), the offset tracking analysis and the difference-of-split-band interferograms (DSI) method (Ozawa and Himematsu, 2022) have some advantages compared to the InSAR analysis. Nevertheless, InSAR provides more accurate and higher-resolution results compared to the other two methods. Therefore, there are advantages in using the InSAR results in fault slip inversions or investigating small features.

The difficulty in the cases of aforementioned significant events lies in the phase unwrapping. Specifically, 1) fault ruptures and other secondary fractures in the fault damage zone which results in phase discontinuities, and 2) dense fringes in highly deformed areas are the main challenges.

In this presentation, we will show how the two challenges can be overcome. The problem of phase discontinuities from the faults and fractures can be resolved by an progressive updating of the mask, and the problem of the dense fringes can be resolved by reducing the number of fringes by subtracting the range-offset results or by iterative unwrapping the phase corresponding to the incremental displacements. In this talk, examples from the 2023 Turkey-Syria Earthquake will be given.