GEOLOGI DAN GEOKIMIA FLUIDA KAWAH SILERI, KOMPLEK GUNUNG API DIENG, JAWA TENGAH, SERTA MEKANISME ERUPSI KAWAH SILERI PADA 2 JULI 2017

• Main Author: Nova Hartanto, Riyan
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/55391
• Institution: Institut Teknologi Bandung

Sileri Crater located at Dieng Plateu, Central Java, has caused hundred victims at the eruptions on 1944 and 1964. Both eruptions and also phreatic eruption at July 2nd 2017 that caused 17 visitors injured became a threat that lurking every time in Dieng Volcanic Complex. Because of that reasons, study about eruption mechanism at Sileri Crater is very important to be done as part of the volcano mitigation. In this study, the data was primary and secondary data. The primary data was from mapping, the secondary data consist of rocks, water and gas chemistry, also data from crater monitoring activity. The analysis methods consist geological analysis, fluid geochemistry analysis, and eruption mechanism analysis. Those methods integrated to make geological synthesis of Dieng Volcanic Complex and eruption model of Sileri Crater. Dieng Volcanic Complex located at Dieng Bregade, consist of six hummocks namely Prau, Nagasari, Bisma, Pagerkandang, Merdada (Merdada and Pangonan Crown), and Seroja (Kendil, Pakuwaja, and Seroja Crown). The activity period devided into 4, those are Pra Caldera, First Period, Second Period, and Last Period. Sileri Crater located specifically at west side of Pagerkandang Volcano. It has heat source from the residual magmatism of Pagerkandang Volcano, with isotope oxygen mixing fraction at 4,28%-21,49% with andesitic water, dominant fluid input from meteoric water. The temperature in reservoir has range between 270oC-350oC. The process of phreatic eruption at Sileri Crater on 2017 are: the fluid in reservoir move upward to surface, separated into steam and dissolved gas that accumulated under the cap rock. The eruption caused by disturbance in soluble gas and steam accumulation by input of meteoric water into crater and hydrothermal system under the crater, magmatism activity, and earthquake, this factors cause the fluid pressure to increase or the cap rock losing its pressure. The eruption caused pressurized steam, mud, and rock to erupt into the area around the crater.