A time-series observation of ground subsidence at Ulsan area using SAR interferometry

The purpose of this study is analysis of surface deformation at Ulsan area using SAR interferometry technique (InSAR). Time-series observation method, Small BAseline Subset (SBAS) and Persistent Scatterer Interferometric SAR (PSInSAR), was also applied for analysis of subtle subsidence which occurred consistently for a long term period. The used dataset consists of twenty-nine SAR images from May 2006 to March 2011. Preliminary results of this study indicate that there are some subsiding districts in Ulsan area. From the mean deformation rate map, one of the most noticeable districts is southern parts of the city where deformation rate decrease gradually from the riverfront of the Taehwa River. The maximum deformation rate estimated from SBAS analysis is -4.4±0.4 cm/yr. Similarly significant rate of -4.0cm/yr was observed from the PSInSAR method on the riverfront and near the Ulsan fault. These results, however, are not yet supported by comparison with the geodetic data. It should be carried out for the more reliable results in further researches.