Garuda - Garba Rujukan Digital

Eka Kadarsetia

Geological Agency, Jalan Diponegoro No. 57 Bandung

Author-ID : 294479

Earth & Planetary Sciences

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Karakteristik kimiawi air danau kawah Gunung Api Kelud, Jawa Timur pasca letusan tahun 1990 Kadarsetia, Eka; Primulyana, Sofyan; Sitinjak, Pretina; Saing, Ugan Boyson
Indonesian Journal on Geoscience Vol 1, No 4 (2006)
Publisher : Geological Agency

http://dx.doi.org/10.17014/ijog.vol1no4.20062Kelud is a strato type volcano characterized by phreatomagmatic and magmatic eruptions. Since last eruption in 1990, the volcano has showed no-more signifi cant volcanism. Currently, there is an opened westward crater lake as a remained eruption crater containing meteoric water and volcanic gases condensate generated from subsurface.Analysis result of lake water exhibits that its chemical composition was fl uctuated due to an infl uence of factors such as seasons, rates of volcanism activity and reactivity of internal chemical elements within the lake water.The volume of lake water increases during the wet season and experiences dilution to make declination of chemical components within the water. Temperature of the lake water increases as well as volcanic intensity, simultaneously to make addition of dissolved chemical compounds and elements such as SO , Cl, B, and F and creates acidic water. Fumarole/solfatara released anykind of gases, such as H O, CO , CO, HCl, SO , H S, HF, H , HBr, NH , CH , H BO , and N . Moreover interaction of andesitic rock and acidic water apparently produces ionic source of Na, K, Ca. Mg, Fe, Al including trace elements such as Zn, Li, Sr, As, Rb, Cr, Pb, Ti, Ni, Cu, Ce, and Be.The composition of crater lake water of the Kelud volcano is included into an immature water category with HCO . The fl uctuation of element, compound and gas contents within the lake water with their depletion trend during the period of 1990 â 2005 may be related to decreasing of volcanism activity in the duration of 1990 post-eruption.Â

Peningkatan kegiatan Gunung Api Tangkubanparahu Jawa Barat pada bulan April 2005 Dana, Isya Nurrahmat; Kadarsetia, Eka; Primulyana, Sofyan; Hendrasto, Muhammad; Nasution, Asnawir
Indonesian Journal on Geoscience Vol 1, No 4 (2006)
Publisher : Geological Agency

http://dx.doi.org/10.17014/ijog.vol1no4.20063Tangkubanparahu 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 ratio of CO /H S, CO /H , and H /Ar, is suggested to indicate the presence of a fast fl uid movement and 2005, shows that the gas is hydrous with the main component of H O, CO , H S and small amount SO ; where CO content is higher than (SO + H S). The gas composition showing high of value from the depth before condensed at the shallow surface water area. Hotspring from the Domas Crater contains a high concentration of SO , low of Cl and absence of H CO . 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.

Characteristics of volcanic gas correlated to the eruption activity; Case study in the Merapi Volcano, periods of 1990-1994 Priatna, Priatna; Kadarsetia, Eka
Indonesian Journal on Geoscience Vol 2, No 4 (2007)
Publisher : Geological Agency

http://dx.doi.org/10.17014/ijog.vol2no4.20074Volcanic gases, collected from Gendol and Woro solfatara fields, the summit of Merapi Volcano during 1990-1994, show an increase in chemical composition of H , CO, CO , SO , and HCl prior to the volcanic events, on the contrary to the drastic decreasing water vapour. The carbon/sulfur ratio of the volcanic gases lies between 1.5 and 5.7 which means that they were derived from the fresh magma. The Apparent Equilibrium Temperature (AET) which is calculated from chemical compositions of volcanic gases using reaction of SO +3H = H S+2H O showed an increasing value prior to the volcanic events. The Merapi activities lasted during August 1990 to November 1994 showed a significant increase in ratio SO /H S prior to the November 1994 pyroclastic flow. The isotopic composition of volcanic gas condensates indicates that water vapour in Gendol is directly derived from the fresh magma. On the other hand, the contamination and cooling by the subsurface water occurred around the Woro field at a shallow part.Â

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