Peningkatan kegiatan Gunung Api Tangkubanparahu Jawa Barat pada bulan April 2005

Abstract

Tangkubanparahu is an active strato volcano located in West Java lying about 30 km to the north of Bandung City. Its crest is 2084 m above the sea level. In order to gain a better understanding on volcanism and magmatism of this volcano, various research and monitoring have been carried out, such as geochemistry and geophysics. Chemical composition of volcanic gases collected from the Ratu Crater (950 C in 1994, 1997, 1998 and 2005, shows that the gas is hydrous with the main component of H2O, CO2, H2S and small amount of SO2; where CO2 content is higher than (SO2 + H2S). The gas composition showing high of value ratio of CO2/H2S, CO2/H2, and H2/Ar, is suggested to indicate the presence of a fast fl uid movement from the depth before condensed at the shallow surface water area. Hotspring from the Domas Crater contains a high concentration of SO4, low of Cl and absence of H2CO3. The high sulphate content is suggested to be originated from the volcanic gases, especially hydrogen sulphide oxydated near the surface, that then the gas infl uenced chemical composition due to shallow water. Continuous seismic monitoring uses one permanent station, while the other methods like Electric Distance Measurement (EDM), Global Positioning System (GPS) and Seismometer have been installed temporary. From geophysical evidence on April 2005 activity, some valuable information can be obtained. Hypocenter is located at the depth less than 2 km beneath an area between the Ratu and Domas Craters, while pressure source of deformation is below Domas Crater. Some low frequency volcanoquakes is possibly caused by volcanic gases released from the reservoir.