Various techniques and methods have been proposed to detect spatially the surface manifestation of a geothermal system using remotely sensed data especially optical sensors. However, the sensors are usually hampered by atmospheric condition and time acquisition problems. Meanwhile, the superiority of the microwave sensors with capability to operate in any weather condition and regardless time acquisition provides accurate surface observation especially at the Torrid Zone such as Indonesia. This paper presents a multi-sensor remote sensing data and applications to calculate spatially the rank of the geothermal potential using Weighted Fuzzy Logic (WFL) method.

The Bacan Island in North Maluku Province, Indonesia was used as study area. The free world-wide Landsat ETM+ combined with ASTER TIR data were used to detect the surface condition in visible to thermal infrared region. Two back-scattering intensity data of ALOS/PALSAR in ascending and descending mode were also used to delineate the geomorphologics and structural features in a microwave region. An integrated application of both data types to assess spatially a geothermal potential will be benefit for a geothermal exploration.

Fig. 1. Study area at Bacan Island, North Maluku, Indonesia presented by black rectangle on the right figure.

Fig. 2. Detected altered minerals as shown by illite, montmorillonite, and alunite (a) and the reference spectra as input of SAM classification (b).

Fig. 3. Surface thermal radiance of ASTER data during daytime (a) and nighttime (b) observation.

Fig. 4. The interpreted-geomorphologic and structural features overlaid on the backscattering intensity of ALOS/PALSAR data.

Fig. 5. The histogram of eight fuzzy membership functions shows a normal distribution in general.

Fig. 6. The map of eight fuzzy membership functions as input of the WFL method.

Fig. 7. The map of WFL presents the rank of geothermal potential from 0 (=no plausible) to 1(=the most plausible). The red circles are the location of the hot springs.

Fig. 8. The rank of geothermal potential in dash curves based on WFL method overlaid on the geological map of Bacan Island modified partly from Yasin, 1980.

Source:

Saepuloh A., Urai M., Sumintadireja P., Suryantini, Spatial priority assessment of geothermal potentials using multi-sensor remote sensing data and applications, proceeding of the 1st ITB Geothermal Workshop 2012, Bandung, Indonesia, March 6, 2012.