Analysis of Surface Displacement Before and After the 2017 Pohang Earthquake using Sentinel-1 PSInSAR Technique

The 5.4 Pohang earthquake occurred on November 15, 2017. It was the second-largest earthquake in South Korea since instrumental earthquake observations began. In this study, the PSInSAR method using Sentinel-1 satellite ascending and descending data were used to analyze the time-series surface displacement of the Pohang area before and after the earthquake. As a result, in the case of PSInSAR result using the descending pass data, surface uplift displacement up to 45 mm in the LOS direction was observed immediately after the earthquake near the epicenter. In addition, to identify the horizontal movement of the co-seismic uplift displacement, it was derived into the vertical component and horizontal component using the results of two different orbital data. And it shows the surface was spreading out into both sides, not just east or west. Besides, continuous subsidence with a velocity of up to 80 mm/year was found in a specific area of the footwall, which was continued before the earthquake. To identify the origin of the subsidence we compared it with the past optical images, and subsidence areas were consistent with the past river topography.