Identification of sub-surface rock structures in the Banyu Biru hot springs area using the gravity method

Luthfin, Ahmad ORCID: https://orcid.org/0000-0001-6121-6807 and Irjan, Irjan (2024) Identification of sub-surface rock structures in the Banyu Biru hot springs area using the gravity method. Jurnal Pendidikan Fisika dan Keilmuan (JPFK), 10 (1). pp. 14-25. ISSN 2442-904X

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Abstract

One of the geothermal manifestations in Nganjuk is the Banyu Biru hot spring in
Gondangwetan Village, Jatikalen District, Nganjuk regency. This hot spring was discovered by
accident when drilling a well to be used as a rice field flow, but the water that came out was hot
water with a temperature of 37 oC at a depth of 250-300 m. This study aims to determine local
anomaly patterns and lithological structures of subsurface rocks in the Jatikalen hot spring area.
The research method used is the gravity method based on GGMPlus satellite data obtained as
many as 100 data with a distance of 200 m between points. Based on the qualitative analysis of
the local anomaly contours, the low anomaly was -2.6 mGal to -0.8 mGal, the moderate
anomaly was -0.6 mGal to 2.2 mGal, and the high anomaly was 0.6 mGal – 2.2 mGal.
Quantitative interpretation with the results of the cross-sectional model resulted in 5 layers of
topsoil with a density value of 1.2 grams/cm3. In the second layer is alluvium in the form of
gravel, gravel, sand with a density of 1.7 grams/cm3. The third layer is tuffaceous clay with a
density of 2 grams/cm3 and the fourth layer is calcareous tuff with a density value of 2.67
grams/cm3. While the last in the fifth layer is breccia rock with a density value of 3 grams/cm3.

Item Type:	Journal Article
Additional Information:	Based on the results of modeling in the hot spring area, it can be concluded that in general there are 5 constituent layers. Where the first layer is topsoil with a density value of 1.2 grams/cm3. In the second layer is alluvium in the form of gravel, gravel, sand with a density of 1.7 grams/cm3. The third layer is tuff aceous clay with a density of 2 grams/cm3 and the fourth layer is calcareous tuff with a density value of 2.67 grams/cm3. While the last in the fifth layer is breccia rock with a density value of 3 grams/cm3
Keywords:	Geothermal; Gravity method; Lithology
Subjects:	04 EARTH SCIENCES > 0404 Geophysics > 040404 Geothermics and Radiometrics 04 EARTH SCIENCES > 0404 Geophysics > 040499 Geophysics not elsewhere classified
Divisions:	Faculty of Mathematics and Sciences > Department of Physics
Depositing User:	M,Si Ahmad Luthfin Ahmad Luthfin
Date Deposited:	30 Oct 2024 11:13

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