Journal of Environmental Engineering & Sustainable Technology JEEST Vol. 02 No. 02, November 2015, Pages 105-113 http://jeest.ub.ac.id P-ISSN:2356-3109 E-ISSN: 2356-3117 105 MULTI GEOPHYSICAL OBSERVATIONS AT BLAWAN - IJEN VOLCANO GEOTHERMAL COMPLEX FOR REGIONAL DEVELOPMENT Sukir Maryanto 1 , Agus S Wicaksono 2 , Anjar P. Azhari 3 , Cinantya N. Dewi 4 , James Foster 5 , Ahmad Nadhir 6 , Abdurrouf 7 1,6,7 Department of Physics, Faculty of Science, Brawijaya University, Malang, Indonesia. 2 Postgraduate Program, Brawijaya University, Malang, Indonesia. 3,4 Postgraduate Program of Physics, Faculty of Science, Brawijaya University, Malang, Indonesia. 5 Hawaii Instittute of Geophysics and Planetary, University of Hawaii, Manoa, USA. Email: 1 sukir@ub.ac.id, 2 agus_caca@yahoo.com, 3 pranggawan.juventini@gmail.com, 4 cinanthiia@gmail.com, 5 jfoster@soest.hawaii.edu, 6 anadhir@ub.ac.id, 7 abdurrouf@ub.ac.id ABSTRACT Geothermal resource investigation by using multi geophysical observation was accomplished for Blawan-Ijen geothermal system. Geological and surface investigation found about 21 hot springs have been found in Blawan area with the surface temperature ranged from about 40 o C-55 o C. Based on resistivity and GPR data known that the underground seepage of hot water following the fault direction. This fault structure is identified based on the high distribution of microseismicity and thermal infrared remote sensing (TIR) analysis which associated with high land surface temperature (LST). Meanwhile, the heat source of Blawan - Ijen geothermal system are found in the southwest part based on high magnetic anomaly which represents the igneous rocks. All methods used shows the results indicating that Blawan-Ijen volcano complex is an interesting area for geothermal energy development and suitable for pilot project on regional development of volcano geothermal region. Keywords: Blawan - Ijen, geothermal, magnetic, microearthquake, TIR, LST. 1. INTRODUCTION The Blawan-Ijen volcano complex, on the eastern tip of Java, occupies a 20 km wide caldera (Fig. 1) formed more than 50,000 years ago as a result of the collapse of the Ijen stratovolcano (van Hinsberg et al., 2010). Ijen volcano is a part of Sunda-Banda volcanic arc stretching from Sumatra to Banda, along 3,700 km which is known to contain a lot of metal ore deposits (Carlile and Mitchell, 1994) and geothermal prospect (Zaennudin et al., 2005; Santoso et al., 2012; Afandi et al., 2013]. Pasqua and Massimo (2014) suggests the presence of a major fault trending East-West along 2 km. The presence of a geothermal system fault structures which are a permeable zone become a way for hot fluid flow out towards the ground as geothermal manifestations (Prabawa et al., 2013). Fig.1. Ijen caldera Blawan-Ijen volcano complex have both geothermal energy resources potential and plantation potential. The primary commodity is coffee, and the other commodities are timber, cabbage, fruits, etc. There is also a coffee factory in Blawan area (Fig. 2). However, the potential of geothermal energy is not fully utilized. Nowadays the source of energy used for society’s activities and a coffee factory in Blawan area still rely on biomass, solar and microhydro. Geothermal energy can be act as a reserve energy around Blawan-Ijen area. Because of the