Time Series InSAR for Ground Deformation Observation in Semarang Area, Central Java

The initiatives of open data and open platforms, combined with on-demand data processing in Synthetic Aperture Radar (SAR), enable more straightforward and accessible ground deformation research worldwide. The Alaska Satellite Facility Distributed Active Archive Center (ASF DAAC) provides high-quality interferogram combination pairs based on the Small Baseline Subset (SBAS) technique and on-demand InSAR data analysis known as HyP3. HyP3 offers unwrapped phase data from Sentinel-1 satellites and other derived products that can be utilized with open-source deformation software such as Mintpy. This research aims to assess the quality of interferogram combination pairs by configuring networks of perpendicular and temporal baselines for observing ground deformation in Semarang, Central Java, Indonesia. The study demonstrates that HyP3 products enable time series analysis to determine deformation rates. Over 8.4 years, from November 15th, 2014, to April 14th, 2023, the Simpang Lima landmark in Semarang experienced an approximate subsidence rate of -0.87 cm/year. However, the maximum subsidence rate of approximately 11 cm/year was observed in the southeastern part of Semarang.