Prof. Sin Mei Ng Department of Geology, Chinese Culture University, Taipei, Taiwan
Synthetic aperture radar (SAR) interferometry was first introduced for topographic mapping in 1974. Essentially it combined two technologies: synthetic aperture and interferometry techniques. When the first interferogram (post-processing interferometric fringes) showing the Landers earthquake was published, more than two decades had elapsed. SAR interferometry and its subsequent developments in the past two decades have successfully proved their capabilities in monitoring crustal deformation and various geophysical applications. This satellite geodetic technique calculates the interference pattern generated by the difference in phase between two images acquired by spaceborne synthetic aperture radar mounted on satellite at distinct times. The resulting interferogram is a contour map of the change in slant range distance.
In this study, pre-seismic, co-seismic, and post-seismic deformation, caused by the latest catastrophic earthquake in Hualien, Taiwan, are investigated, using a comparable, newly-developed InSAR processing system based on Generic Mapping Tools, GMTSAR and ESA’s Sentinel-1A data. This shallow (focal depth = 6.31 km), moderate-sized (ML 6.26) but devastating earthquake occurred in Taiwan region at 15:50:41 (UTC) on February 6, 2018. According to the Geophysical Data Management System (GDMS), Central Weather Bureau, Taiwan, the epicenter, 121.73°E, 24.1°N, is located offshore Hualien city. It caused severe casualties: 17 deaths and 291 injured; and, five buildings were marked as red flags.