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Report on Merapi (Indonesia) — September 1978

Scientific Event Alert Network Bulletin, vol. 3, no. 9 (September 1978)
Managing Editor: David Squires.

Merapi (Indonesia) Fumarole temperatures and gas analyses

Please cite this report as:

Global Volcanism Program, 1978. Report on Merapi (Indonesia) (Squires, D., ed.). Scientific Event Alert Network Bulletin, 3:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN197809-263250.

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7.54°S, 110.446°E; summit elev. 2910 m

All times are local (unless otherwise noted)

Franois Le Guern and Haroun Tazieff provided the following fumarole temperatures and gas compositions (table 2), obtained during their July visit to Merapi. Gases were analyzed with a field gas chromatograph.

Table 2. Fumarole temperatures (maximum and analyzed with a gas chromatograph) and gas compositions (in volume %) at Merapi, July 1978. "Crater" is the crater near the active dome. Courtesy of Franois LeGuern and Haroun Tazieff.

Location Gendol(1) Gendol(2) Gendol(3) Crater Woro
Max Temp °C 820 -- -- 901 760
Analysis Temp °C 720 720 819 744 580
CH4 0.013 0.017 less than 0.001 0.06 --
CO2 3.28 4.02 4.57 5.26 3.21
H2O 94.37 93.08 93.71 90.75 94.27
H2S 0.24 0.30 0.47 1.15 0.12
SO2 0.25 0.31 0.51 1.14 0.06
H2 1.12 1.36 0.56 1.46 Tr
O2+Ar 0.15 0.19 0.005 0.02 Tr
N 0.55 0.68 0.13 0.12 2.34
CO 0.03 0.03 0.01 0.02 0.02

Geologic Background. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2,000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequent growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities.

Information Contacts: F. LeGuern and H. Tazieff, CNRS, Gif-sur-Yvette.