Subsurface density architecture of the Sibualbuali geothermal area, north Sumatra, inferred from GGMplus gravity data and 3D inversion

Singgih Hidayat; Yosi Setiawan; Nadiyah Az Zuhriyyah; Lailatul Husna Lubis; Nivedita Chaubal-Durve; Arti Hadap

doi:10.58524/jograv.v1i2.186

Authors

Singgih Hidayat Department of Physics, Science and Technology of Faculty, Universitas Islam Negeri Sumatera Utara Author
Yosi Setiawan Department of Physics, Science and Technology of Faculty, Universitas Islam Negeri Sumatera Utara Author
Nadiyah Az Zuhriyyah Department of Physics, Science and Technology of Faculty, Universitas Islam Negeri Sumatera Utara Author
Lailatul Husna Lubis Department of Physics, Science and Technology of Faculty, Universitas Islam Negeri Sumatera Utara Author
Nivedita Chaubal-Durve Mukesh Patel Scool of Technology Management and Engineering Author
Arti Hadap MPSTME, SVKM's Narsee Monjee Institute of Management Studies (NMIMS) Author

DOI:

https://doi.org/10.58524/jograv.v1i2.186

Keywords:

GGMplus, Gravity inversion, Subsurface density, Geothermal system, Mount Sibualbuali

Abstract

Mount Sibualbuali in South Tapanuli, North Sumatra, is an active geothermal area characterized by volcanic structures and surface manifestations, including hot springs, warm ground, steaming ground, and fumaroles. However, the subsurface density architecture and its relationship to the geothermal system remain insufficiently constrained. This study investigates the gravity-derived subsurface structure of the Sibualbuali geothermal area using secondary Global Gravity Model Plus (GGMplus) data integrated with Complete Bouguer Anomaly analysis, spectral analysis, regional–residual separation, and three-dimensional gravity inversion. The Complete Bouguer Anomaly ranges approximately from −17 to 5 mGal and exhibits contrasting gravity patterns across the study area. Spectral analysis along eight profiles indicates mean characteristic depths of approximately 3.48 km for the deeper regional component and 0.70 km for the shallower residual component. Regional–residual separation further reveals localized gravity variations associated with shallow density contrasts. The 3D inversion resolves heterogeneous subsurface density domains that are interpreted in relation to the regional geological framework. Low-density material with an average density of approximately 2.35 g/cm³ is broadly consistent with sedimentary, altered, or highly fractured rocks, whereas intermediate-density material of approximately 2.56 g/cm³ is compatible with volcanic rocks. Higher-density domains averaging approximately 2.68 g/cm³ are consistent with denser intrusive or basement-related rocks. A relatively low-density body occurs within the modeled geothermal area and may represent a structurally controlled, altered, or reservoir-related zone; however, gravity data alone do not uniquely constrain permeability, fluid content, or thermal state. The results provide a regional framework for understanding the subsurface density architecture beneath Mount Sibualbuali and highlight zones that warrant further evaluation using independent geophysical, geological, and geochemical constraints.

References

1. Asy’ari, M. F. (2019). Identifikasi Sebaran Batubara Menggunakan Metode Gravity di Lapangan “X”, Undergraduate Thesis, Universitas Islam Negeri Maulana Malik Ibrahim, Malang, Indonesia.

2. Aulia, M. R., Putranto, T. T., and Setyawan, R. (2020). Karakteristik Reservoir Berdasarkan Analisis Petrofisik pada Formasi Baturaja, Lapangan Aulia, Cekungan Jawa Barat Utara, Jurnal Geosains dan Teknologi, Vol. 3, No. 1, pp. 31–41. doi:10.14710/jgt.3.1.2020.31-41.

3. Fanani, M. I. (2014). Interpretasi Struktur Bawah Permukaan Daerah Potensi Panas Bumi Berdasarkan Data Geomagnetik: Studi Kasus di Daerah Sumber Air Panas Desa Lombang, Kecamatan Batang-Batang, Kabupaten Sumenep, Undergraduate Thesis.

4. Gunawan, Y. (2022). Pemodelan 3D Densitas Bawah Permukaan Berdasarkan Data Gravitasi di Daerah Gunung Gede Jawa Barat, Undergraduate Thesis, Faculty of Science and Technology, Universitas Islam Negeri Syarif Hidayatullah Jakarta, Indonesia.

5. Gusnia, E., Kusmita, T., and Indriawati, A. (2022). Analisis Anomali Gravity Daerah Panas Bumi Non-Vulkanik di Bangka Tengah: Studi Kasus Panas Bumi Terak dan Keretak, Jurnal Riset Fisika Indonesia, Vol. 2, No. 2, pp. 1–7. doi:10.33019/jrfi.v2i2.3233.

6. Hirt, C., Claessens, S., Fecher, T., Kuhn, M., Pail, R., and Rexer, M. (2013). New Ultrahigh-Resolution Picture of Earth’s Gravity Field, Geophysical Research Letters, Vol. 40, No. 16, pp. 4279–4283. doi:10.1002/grl.50838.

7. Indratmoko, P., Nurwidyanto, M. I., and Yulianto, T. (2009). Interpretasi Bawah Permukaan Daerah Manifestasi Panas Bumi Parangtritis Kabupaten Bantul DIY dengan Metode Magnetik, Berkala Fisika, Vol. 12, No. 4, pp. 153–160.

8. Jamaluddin, Maria, Ryka, H., and Afifah, R. S. (2019). Pemodelan Bawah Permukaan Bantar Karet, Jawa Barat Menggunakan Metode Gravitasi, Jurnal Geocelebes, Vol. 3, No. 2, pp. 59–65. doi:10.20956/geocelebes.v3i2.6689.

9. Juliani, R. (2013). Analisa Air dan Pola Penyebaran Resistivitas Batuan Bawah Permukaan di Daerah Panas Bumi Sibual-Buali Tapanuli Selatan, EINSTEIN (e-Journal), Vol. 1, No. 2. doi:10.24114/einstein.v1i2.5058.

10. Kamilah, A. (2022). Identifikasi Struktur Batuan Bawah Permukaan di Daerah Pemandian Air Panas Banyu Biru Menggunakan Metode Gravitasi, Undergraduate Thesis.

11. Liana, Y. R., Wea, T. M. M., Syarifah, W., Supriyadi, and Khumaedi. (2020). Analisis Anomali Bouguer Data Gaya Berat: Studi Kasus di Kota Lama Semarang, JRST (Jurnal Riset Sains dan Teknologi), Vol. 4, No. 2, pp. 63–68. doi:10.30595/jrst.v4i2.6301.

12. Putri, D. R., et al. (2019). Interpretation of Gravity Satellite Data to Delineate Structural Features Connected to Geothermal Resources at Bur Ni Geureudong Geothermal Field, IOP Conference Series: Earth and Environmental Science, Vol. 364, 012003. doi:10.1088/1755-1315/364/1/012003.

13. Sarkowi, M., and Wibowo, R. C. (2021). Geothermal Reservoir Identification Based on Gravity Data Analysis in Rajabasa Area, Lampung, Riset Geologi dan Pertambangan, Vol. 31, No. 2. doi:10.14203/risetgeotam2021.v31.1164.

14. Setiadi, I., Diyanti, A., and Ardi, N. D. (2014). Interpretasi Struktur Geologi Bawah Permukaan Daerah Leuwidamar Berdasarkan Analisis Spektral Data Gaya Berat, Jurnal Geologi dan Sumberdaya Mineral, Vol. 15, No. 4, pp. 205–214. doi:10.33332/jgsm.geologi.v15i4.59.

15. Sudrajad, B. (2023). Analisis Deskriptif Perbandingan Data Sekunder Gravitasi GGMplus terhadap Data Gravitasi Lapangan Panas Bumi Gunung Lawu dan Data Gravitasi Stasiun Referensi (Gravity Base Station) di Pulau Papua, Jurnal Fisika Papua, Vol. 2, No. 1, pp. 25–34. doi:10.31957/jfp.v2i1.22.

16. Sulistyawan, I., and Harahap, B. (2013). Magmatisme, Sumberdaya Mineral dan Energi di Tapanuli Selatan–Sumatera Utara, Jurnal Sumber Daya Geologi, Vol. 23, No. 3, pp. 167–177.

17. Telford, W. M., Geldart, L. P., and Sheriff, R. E. (1990). Applied Geophysics, 2nd ed., Cambridge University Press, Cambridge, UK.

18. Zulfayani, I. (2022). Identifikasi Sistem Panas Bumi Berdasarkan Analisis Gradien Gaya Berat dan Pemodelan Anomali Gaya Berat Lapangan Panas Bumi Kamojang, Undergraduate Thesis, Faculty of Engineering, Universitas Lampung, Bandar Lampung, Indonesia.

19. Maryanto, S. (2017). Geo Techno Park Potential at Arjuno-Welirang Volcano Hosted Geothermal Area, Batu, East Java, Indonesia (Multi Geophysical Approach), AIP Conference Proceedings, Vol. 1908, No. 2017. doi:10.1063/1.5012712.

20. Sujitapan, C., Kendall, J. M., Chambers, J. E., and Yordkayhun, S. (2024). Landslide Assessment through Integrated Geoelectrical and Seismic Methods: A Case Study in Thungsong Site, Southern Thailand, Heliyon, Vol. 10, No. 2. doi:10.1016/j.heliyon.2024.e24660.

21. Chambers, J., Holmes, J., Whiteley, J., Boyd, J., Meldrum, P., Wilkinson, P., Kuras, O., Swift, R., Harrison, H., Glendinning, S., Stirling, R., Huntley, D., Slater, N., and Donohue, S. (2022). Long-Term Geoelectrical Monitoring of Landslides in Natural and Engineered Slopes, Leading Edge, Vol. 41, No. 11, 768–767. doi:10.1190/tle41110768.1.

22. Whiteley, J. S., Watlet, A., Uhlemann, S., Wilkinson, P., Boyd, J. P., Jordan, C., Kendall, J. M., and Chambers, J. E. (2021). Rapid Characterisation of Landslide Heterogeneity Using Unsupervised Classification of Electrical Resistivity and Seismic Refraction Surveys, Engineering Geology, Vol. 290, No. May, 106189. doi:10.1016/j.enggeo.2021.106189.

23. Martinho, E. (2023). Electrical Resistivity and Induced Polarization Methods for Environmental Investigations: An Overview, Water, Air, and Soil Pollution, Vol. 234. doi:10.1007/s11270-023-06214-x.

24. Kusumayudha, S. B., Lestari, P., and Paripurno, E. T. (2018). Eruption Characteristic of the Sleeping Volcano, Sinabung, North Sumatera, Indonesia, and SMS Gateway for Disaster Early Warning System, Indonesian Journal of Geography, Vol. 50, No. 1, pp. 70–77. doi:10.22146/ijg.17574.

25. Meju, M. A., and Le, L. (2002). Geoelectromagnetic Exploration for Natural Resources: Models, Case Studies and Challenges, Surveys in Geophysics, Vol. 23, pp. 133–205.

26. Lange, D., Tilmann, F., Henstock, T., Rietbrock, A., Natawidjaja, D., and Kopp, H. (2018). Structure of the Central Sumatran Subduction Zone Revealed by Local Earthquake Travel-Time Tomography Using an Amphibious Network, Solid Earth, Vol. 9, No. 4, pp. 1035–1049. doi:10.5194/se-9-1035-2018.

27. Lin, J. Y., Sibuet, J. C., Hsu, S. K., and Wu, W. N. (2014). Could a Sumatra-like Megathrust Earthquake Occur in the South Ryukyu Subduction Zone?, Earth, Planets and Space, Vol. 66, No. 1, pp. 1–8. doi:10.1186/1880-5981-66-49.

28. Siringoringo, L. P., Sapiie, B., Rudyawan, A., and Sucipta, I. G. B. E. (2024). Origin of High Heat Flow in the Back-Arc Basins of Sumatra: An Opportunity for Geothermal Energy Development, Energy Geoscience, Vol. 5, No. 3, 100289. doi:10.1016/j.engeos.2024.100289.

29. Hochstein, M. P., and Sudarman, S. (1993). Geothermal Resources of Sumatra, Geothermics, Vol. 22, No. 3, pp. 181–200. doi:10.1016/0375-6505(93)90042-L.