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All Journal IJOG : Indonesian Journal on Geoscience
Sofyan Primulyana
Pusat Vulkanologi dan Mitigasi Bencana Geologi, Jln. Diponegoro No. 57, Bandung
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

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (601.78 KB) | DOI: 10.17014/ijog.v1i4.20

Abstract

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 – 2005 may be related to decreasing of volcanism activity in the duration of 1990 post-eruption. 
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

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (545.362 KB) | DOI: 10.17014/ijog.v1i4.21

Abstract

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.
Explosive Signature of The April 30th, 2024 Ruang Volcano Eruption in The Sangihe Arc, Indonesia, Inferred from Erupted Material Characteristics: A Preliminary Assessment Purnamasari, Heruningtyas Desi; Saepuloh, Asep; Primulyana, Sofyan; Adriansyah, David; Prayoga, Ardy Setya; Agustiningtyas, Lestari; Wijaya, P. Hadi; Gunawan, Hendra
Indonesian Journal on Geoscience Vol. 12 No. 3 (2025)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.12.3.11-17

Abstract

The 2024 eruptions of Ruang Volcano in North Sulawesi, Indonesia, represent one of the most explosive and impactful volcanic events in the region's recent history. The eruption sequence, which commenced on April 16th and peaked with significant explosive episodes on April 17th and 30th, resulted in the evacuation of over 9,000 residents and demonstrated the volcano’s capacity for high-energy eruptive activity. This preliminary analysis of the April 30, 2024, Ruang Volcano eruption emphasises the importance of ejected materials—such as high-vesicular juvenile fragments, crystal-rich components, and megacrysts of amphibole (hornblende)—in revealing the eruption’s explosive signature. Geochemical analysis of juvenile materials indicates a basaltic andesite composition, with SiO₂ contents ranging from 53.02% to 54.27%. Petrographic examination and SEM observations reveal high vesicularity, ruptured bubble walls, and microlite-rich groundmass textures, indicative of rapid ascent and intense degassing, which facilitated efficient magma fragmentation. These features suggest that the magma underwent rapid decompression. Understanding these properties provides important clues about the mechanisms underlying the explosiveness of the Ruang eruption.
Co-Authors Adriansyah, David Agustiningtyas, Lestari Asep Saepuloh Asnawir Nasution Eka Kadarsetia HENDRA GUNAWAN B11211055 Isya Nurrahmat Dana Muhammad Hendrasto Prayoga, Ardy Setya Pretina Sitinjak Purnamasari, Heruningtyas Desi Ugan Boyson Saing Wijaya, P. Hadi