Daerah panas bumi Wapsalit berada di Pulau Buru, Maluku, Indonesia yang secara geologi berada pada lingkungan non-vulkanik. Berdasarkan penyelidikan terdahulu, daerah ini memiliki prospek panas bumi di sekitar area manifestasi panas bumi yang dikontrol oleh perpotongan dua sesar. Proses inversi 2-Dimensi dari data magnetotellurik (MT) dilakukan untuk menggambarkan sebaran tahanan jenis batuan bawah permukaan. Proses inversi ini menggunakan algoritma Active Constraint Balancing (ACB) yang memanfaatkan prinsip spatially variable regularization parameter. Lapisan konduktif yang berfungsi sebagai lapisan penudung berupa batuan metamorf terubah muncul di dekat permukaan hingga kedalaman 1000 – 1250 meter. Lapisan ini semakin meninggi seiring dengan kedalaman yang mengindikasikan zona reservoir. Zona tahanan jenis tinggi (resistif) dengan bentuk kubah muncul pada bagian bawah yang diinterpretasikan sebagai batuan intrusif muda

These days, the number of geothermal explorations is being increased to obtain a greater new potential of geothermal energy. One of the methods that is often used is magnetotelluric (MT). By MT, the components of a geothermal system can be delineated based on the resistivity values. This research’s main purpose is MT data modelling in 1 D and 2 D to delineate the geothermal system in the research area. There are 18 point of soundings, with a distance of about 1 – 3 km for each point. Bostick Transformation is used in 1 D modelling while Non-Linear Conjugate Gradient inversion is used as 2 D modelling with L – curve analysis as a method to obtain an optimal value of regularization parameter. Based on the analysis of 1 and 2 D models, the caprock zone was identified with a resistivity value of < 50 Ωm at a depth of 500 m with a thickness of about 250 m. The reservoir zone was identified with a resistivity value range of (50 – 100) Ωm located at a depth of 1000 with a thickness of about 500 m. Also, fault structures have been identified at the center of the research area. The regularization parameter used for the 2 D modelling is 5, which has obtained RMS values of 2.25% and 2.21% for each line.

West Sumatra is one of a geothermal potential in Indonesia because of interaction between Eurasian and Indo-Australian tectonic. The existence of volcanoes produces geothermal potential with lithology andesite, tuff, and lapilli lava in the Marapi Mountain complex, which elongated at NW-SE direction as a result of NE-SW subduction. The remote sensing method specifically with Composite Band 567 and Lineament Density Analysis (LDA) found anomaly with the permeability value of prospects ranged from 2.05 to 4.76% per km2 (highest density value) with general direction is in the southeast-northwest which in line with the Sumatra structural pattern.  Based on geological data, argillic alteration was found with geothermal manifestations consisting of hot springs. Through geochemical analysis, the fluid type of hot water sample (temperature of 48.66oC) is in the immature water zone; occur with the presence of carbonate sinter. Geophysical analysis using the magnetotelluric (MT) method to identified geothermal systems such as cap rock with low resistivity (<30 ohm.m) and reservoirs with moderate resistivity (31-300 ohm.m). The correlation between remote sensing, geochemistry, and magnetotelluric could determine the geothermal potential in West Sumatra.

Metode magnetotellurik (MT) dapat menggambarkan struktur/zona tahanan jenis rendah di daerah panas bumi yang dapat ditafsirkan sebagai lapisan batuan penudung. Zona-zona ini biasanya digunakan untuk membantu penentuan target wellsite dan memperkirakan potensi/kapasitas sumber daya panas bumi. Dalam pemprosesan data MT, dapat dilakukan dengan pemodelan inversi 1-D, 2-D, dan 3-D untuk menghasilkan model yang realistis dan lebih presisi. Pemodelan Inversi 1-D sangat mudah dilakukan, disamping itu dapat digunakan sebagai jaminan kualitas setiap stasiun data MT yang lebih efektif. Inversi 1-D biasanya dapat menggambarkan karakter geometri dari tahanan jenis secara keseluruhan terhadap lapisan penudung, namun tidak dapat mendeteksi batas bawah atau variasi kedalamannya. Untuk menjawab ketidakpastian tersebut, dapat dilakukan pemodelan inversi 2-D. Namun pemodelan inversi 2-D juga tidak akan dapat berhasil baik, jika mendapatkan kondisi geologi yang kompleks di daerah penyelidikan. Keterbatasan dari pemodelan inversi 1-D dan 2-D tersebut, dapat diatasi dengan melakukan pemodelan inversi 3-D. Perbandingan metode pemodelan ini dilakukan dengan menggunakan data MT di daerah panas bumi Lokop, Provinsi Aceh. Hasil pemodelan 1-D dan 3-D lebih dapat menggambarkan kemungkinan adanya zona lapisan penudung di daerah panas bumi Lokop.

Geothermal energy is a clean alternative energy resource. Southern Ogan Komering Ulu (OKU), South Sumatera, is a geothermal prospect area because of the interaction between the Eurasian and Indo-Australian tectonic plates. It causes geological structures growth and the activity of volcanism in the area. Based on geological data, geothermal in southern OKU is indicated by the existence of 40-93 ºC temperature hot springs. Geological data based on remote sensing methods can determine the lineament. Geophysical data with gravity and magnetotelluric can identify the type of rock and the subsurface geological structure based on rock density and resistivity. Based on geological and gravity data indicates the presence of geological formations lead northwest-southeast, which is estimated as the geothermal fluid pathway with the suitability to the location of hot springs. The magnetotelluric data shows the geothermal reservoir rocks (clastic sedimentary rock) located at (-500)-(-2.500) meters depth with 30-200 Ωm resistivity.