Journal of Environmental Engineering & Sustainable Technology JEEST Vol. 07 No. 02, November 2020, Pages 18-25 http://jeest.ub.ac.id 18 P-ISSN:2356-3109 E-ISSN: 2356-3117 IDENTIFICATION OF KAWI-SONGGORITI GEOTHERMAL PROSPECTS BASED ON FAULT AND FRACTURE DENSITY (FFD) Nur Aini Gama Lestari 1 , Sukir Maryanto 2 , Didik Rahadi Santoso 2 1 Physics Postgraduate Program, Faculty of Mathematics and Natural Science, University of Brawijaya 2 Department of Physics, Faculty of Mathematics and Natural Science Email: 1 aini.gama@gmail.com, 2 sukir@ub.ac.id, 2 dieks@ub.ac.id ABSTRACT This research aimed to identify the surface structures of geothermal area in Kawi- Songgoriti based on lineament density and surface manifestation. The lineaments can be extracted from digital elevation model (DEM) via PCI Geomatica and Arcgis. The surface structures were analyzed through the density of lineaments on the surface using FFD method. It is assumed that the lineaments are associated with fractures or faults found in geothermal areas. Those fractures are generally covered by surface manifestations which are hard to identify. These faults and fractures are assumed to be weak lines that act as fluid thermal movement, thereby they can indicate the location of permeable area or a reservoir. As a result, the high lineament density in Kawi assumed to be the control of Songgoriti manifestation. Keywords: FFD, geothermal, lineament, DEM, Kawi, Songgoriti 1. INTRODUCTION The research area is situated in Kawi- Songgoriti geothermal prospect area. Morphologically, the research site is located in mountainous area in the form of steep slopes, wide to narrow and deep valleys. The steep morphology resulted in limited field data acquisition so that satellite imagery analyses would prove to be more effective for preliminary study prior to field data collection. Remote sensing through satellite images has been widely used in geothermal exploration, especially in preliminary studies to determine lineament patterns and studies of volcanic bodies using DEM (digital elevation map) images. ((Iqbal and Juliarka, 2019). Lineaments are one of the most important properties indicating subsurface elements or structural weakness, such as faults, and are usually extracted by visual analysis of enhanced image data (Abdullah, 2012). The DEM data are the processed through relief shading that aims to improve the image data by providing a 3-dimensional effect. This method provides topographic map in natural and aesthetical manner (Alhirmizy, 2013) . The Fault and Fracture Density (FFD) method is a development of geospatial analysis that can be used to determine the condition of the macro structure (Yanis et al., 2019). FFD method is based on the calculation of the lineation of density pattern in the satellite image which is assumed to be a weak zone. The weak zone may be a topographic expression of faults, joints or other line weakness. Moreover, the lineaments may have a geomorphological expressions, i.e terraces, cliffs, ridges (Thannoun, 2013). Additionally, the weak zone can indicate a thermal fluid flow path that leads one to speculate that it is the location of a steam reservoir or reservoir zone (Bujung et al., 2011). Thermal fluids can flow mainly through fractures and fault zones that interact with the surrounding rock and exhibit lineament patterns. Fractures and faults that develop around intrusion bodies are potentially permeable zones that can act as pathways for thermal fluids to flow from reservoirs at depth to shallower levels (Suryantini and Wibowo, 2010). Studying fault patterns and fracture zones, can guide on to indications of productive areas in a geothermal reservoir. Songgoriti geothermal system is formed by the Kawi-Butak Volcano Complex (Figure 1). Physiographycally, the research area is situated in the Solo-Volcano Quaternary East Java Lane which is flanked by the Kendeng