Volcanic Landforms that Mark the Successfully Developed Geothermal Systems of Java, Indonesia Identified from ASTER Satellite Imagery

Abstract

The ASTER Volcano Archive (AVA) provides very near- infrared 15 m pixel satellite images of volcanic centres worldwide. The images’ utility in this instance is their availability and widespread coverage rather than their spectra. The archive includes the volcanic centres hosting the successfully developed geothermal systems of Awibengkok, Wayang Windu, Darajat, Kamojang, and Dieng on the island of Java, Indonesia.
Volcanic landforms associated with the successfully developed geothermal fields on Java can be identified from the ASTER images as large andesitic stratovolcanos, calderas, resurgent volcanism, sector collapses and maars. Of these features; stratovolcanos, calderas, sector collapses and resurgent volcanism can be interpreted to be found at all of these fields. Maars are found only at Dieng.
The calderas predate sector collapses and maars. There is a closer correspondence between the respective locations of the known productive resources to major sector collapses than to calderas. Sector collapse locations at Darajat and Kamojang are interpreted to be at least partially controlled by the caldera margin location, where one side of the caldera collapsed. Since weakening of the volcanic pile by widespread hydrothermal alteration with ongoing geothermal activity is a strong mechanisms for major late stage sector collapses, these are possibly the most indicative landform of the presence of an exploitable geothermal field.
The volcanic landforms common to these fields can be identified and looked for in volcanic centres elsewhere on Java, Bali and possibly island arcs worldwide in order to evaluate potential geothermal prospects. Not only does this obviate the potentially limited public availability of other high quality exploration data, but it may identify blind prospects.