Interpretation Of Bouguer Anomaly To Determine Fault And Subsurface Structure At Blawan-Ijen Geothermal Area

Anjar Pranggawan Azhari, Sukir Maryanto, Arief Rachmansyah

Gravity survey has been acquired by Gravimeter Lacoste & Romberg G-1035 at Blawan-Ijen geothermal area. It was a focusing study from previous research. The residual Bouguer anomaly data was obtain after applying gravity data reduction, reduction to horizontal plane, and upward continuation. Result of Bouguer anomaly interpretation shows occurrence of new faults and their relative movement. Blawan fault (F1), F2, F3, and F6 are normal fault. Blawan fault is main fault controlling hot springs at Blawan-Ijen geothermal area. F4 and F5 are oblique fault and forming a graben at Banyupahit River. F7 is reverse fault. Subsurface model shows that Blawan-Ijen geothermal area was dominated by the Ijen caldera forming ignimbrite (ρ1=2.670 g/cm3), embedded shale and sand (ρ2=2.644 g/cm3) as Blawan lake sediments, magma intrusion (ρ3=2.814 g/cm3 & ρ7=2.821 g/cm3), andesite rock (ρ4=2.448 g/cm3) as geothermal reservoir, pyroclastic air fall deposits (ρ5=2.613 g/cm3) from Mt. Blau, and lava flow (ρ6=2.890 g/cm3).


Identifikasi Struktur Geologi Dan Pengaruhnya Terhadap Suhu Permukaan Tanah Berdasarkan Data Landsat 8 Di Lapangan Panasbumi Blawan

Anjar Pranggawan Azhari, Sukir Maryanto, Arief Rachmansyah

This paper presented used remote sensing method for identification geological structure on Blawan-Ijengeothermal field and its system. Remote sensing data, specifically Landsat 8 and DEM SRTM, provide lineaments from the 753 multispectral band and the land surface temperature (LST) from single thermal infra red band using a retrieval method. Surface emissivity was determined based on Normalized Difference Vegetation Index (NDVI) of study area. Remote sensing analysis is good approach to identification of geological structure from surface that control thermal manifestation in Blawan geothermal field. It shows Blawan fault is the main structure in geothermal field which associated with high LST and hot springs. Interpretation indicated reservoir of Blawan-Ijen geothermal system spread from Plalangan to southwest area.