This edition of Eksplorium contains five (5) papers. The first paper is titled “Volcanic Ash Fall Hazard of Mount Merapi on Yogyakarta Nuclear Area.” The second paper is titled “Geology and Alteration of East Pinolosian Area, Bolaang Mongondow, North Sulawesi Province." The third paper is titled “Petrogenesis and Geological Structure of Tantan Granitoid in Sungai Manau District, Merangin Regency, Jambi Province.” The fourth paper is titled “Geological Structure Control on the Formation of Metal Mineralization at Quartz Veins in Jendi Village, Wonogiri Regency, Central Java.” The fifth paper is titled “Activation of Kaolin Minerals from Ketapang Regency as Cu Metal Adsorbent Material.”