SURFACE DEFORMATION ANALYSIS USING PERSISTENT SCATTERER INTERFEROMETRIC SYNTHETIC APERTURE RADAR (PS-INSAR) METHOD FOR SARULLA GEOTHERMAL FIELD DEVELOPMENT

• Main Author: Maulana, Yahya
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/77516
• Institution: Institut Teknologi Bandung

The Sarulla geothermal field has two exploited prospect areas since 2017, namely Namora-I-Langit and Silangkitang, and two unexploited prospect areas, namely Donotasik and Sibualbuali. The study on surface deformation in the Sarulla region aims to analyze the deformation characteristics caused by fluid extraction and injection activities, as well as tectonic activities around the Sumatra Great Fault. The surface deformation characteristics observed in the exploited areas are subsequently used to aid the analysis of exploration targets in the unexploited areas. The Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) method is applied to detect surface deformation phenomena in areas with persistent scatterers (PS) values. Furthermore, the kriging estimation method is applied to estimate deformation values in non-PS areas, referred to as distributed scatterers (DS). SAR images used in this study are from SENTINEL-1A with both ascending and descending orbit directions, recorded between 2017 and 2021. Geophysical data in the form of microgravity and microearthquake data are used as supporting data to interpret the causes of deformation. The average deformation rate in the study area amounts to 0.39 mm/year with a standard deviation of 2.56 mm/year, defining the threshold for normal deformation. Anomalies in the deformation rate exceeding this threshold are likely attributed to geothermal exploitation, tectonic activity, or a combination of both. Geothermal exploitation activities in Namora-I-Langit and Silangkitang induce highly significant deformation anomalies ranging from -18 to 15 mm/year. Deformation resulting from tectonic activities shows anomalies of approximately ±5 mm/year in the vicinity of the Great Sumatra Fault. In the unexploited areas of Donotasik and Sibualbuali, notable deformation anomalies of around ±5 mm/year are observed, suggesting the presence of fault zones as permeable zones.