The 3 rd International Symposium for Sustainable Humanosphere (ISSH) A Forum of Humanosphere Science School (HSS) Bengkulu, 17 -18 September 2013 CALCULATION OF DISASTER RISK VALUE IN THE PROSPECT MINING AREA, BLITAR DISTRICT, EAST JAVA USING MICROTREMOR ANALYSIS Diyan Parwatiningtyas 1 *, Erlin Windia Ambarsari 2 , Dwi Marlina 3 , Yogi Wiratomo 4 1 Departement of Physich, Faculty of Enggineering, Mathematics and Natural Sciences, Universitas Indraprasta PGRI, Jl. Nangka No.58C Tanjung Barat, Jakarta Selatan *Corresponding author: diane.tyas@gmail.com Abstract Indonesia has a wealth of natural resources is so large to be managed and utilized, both by the government and local communities themselves, particularly in the mining sector. However, mining exploitation can change the state of the surface layer of the earth that have a high disaster risk. This could threaten the safety and disrupt human life, environmental damage, loss of property, and the psychological impact, as referring to the law No. 24 of 2007 on disaster management. In this study, we propose a way to manage and minimize the risk of bentonite mine disasters in the region, by using the calculation method of Amplification Factor (AF) based on microtremor analysis of Kanai and Nakamura interpretation . Based on the amplification factor obtained, some area in blitar district showed instability in the surface layer of a mining area include the site of the TP-7, TP-8, TP-9, TP-10, (Birowo 2 Area). If we analys it in terms of structure, the location of this indicated unstable, because it has a sloping surface layer, resulting in the occurrence of landslides and high seismic risk . In the meantime, other areas (Birowo 1 and Ringinrejo Area)of the mine site can be said to be a stable area. Keywords: Risk Reduction, Microtremor Analysis, Interpretation of surface layer Referring to the value of the Disaster Risk by Amplification Factor Introduction Bentonite mining acvities will alter Earth's surface layer becomes unstable. If this is allowed, then it will lead to a high risk of disasters, especially landslides. According to the head of departement of energy and mineral mineral resources, the province of East Java, Ir. Dewi J. Putriani MSc (2010)[5], “if mining exploitation management is done wihout seeing the seriously impact, then our children and grand children would be bear later” ( The information and communication services of East Java Province, 2010). So, In this study, we propose a way to manage and reduce disaster risk in the mining prospects using the Amplification Factor (AF) of microtremor analysis. The study area is a bentonite mining, located in Blitar district, East Java Province, within the coordinates of 112 0 18'20"E to 112 o 22' 26” E and 8 0 12'09"S to 8 0 05'15"S. This region is a mountainous area with steep valleys in the southern part of East Java. It stretches from Pacitan, Ponorogo, Trenggalek, Tulungagung, Blitar, Malang southand Jember. Access to the area is difficult due to itsrough morphology and the possibility of natural disasters. These problems include landslides, earthquakes, and tsunamis on the beach ramps. There is also potential to develop mining projects for natural resources such as metals and minerals (gold, copper, zeolite, bentonite) and in certain locations limestone and andesite. Tourism can also benefit in the area with activities such as whitewater rafting and tours in limestone caves (Van Bemmelen, 2005)[6].