Report on Momotombo (Nicaragua) — July 1981

Scientific Event Alert Network Bulletin, vol. 6, no. 7 (July 1981)
Managing Editor: Lindsay McClelland

Momotombo (Nicaragua) Medium-to-high temperature gases collected

Please cite this report as:

Global Volcanism Program, 1981. Report on Momotombo (Nicaragua). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 6:7. Smithsonian Institution.

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12.422°N, 86.54°W; summit elev. 1297 m

All times are local (unless otherwise noted)

Between 14 June and 11 July, personnel from PIRPSEV, CNRS, and the volcano observation section of IPG sampled medium-to-high temperature gases from Momotombo (table 1). Maximum gas temperatures measured were 640°C.

Table 1. Analytical mean of four mid-1981 gas samples (dry, HCl excluded) from Momotombo. Courtesy of H. DeLorme and J. Cheminée.

Component Mean Value
SO2 24.02%
CO2 64.86%
H2 4.89%
H2S 6.15%
N2 4.93% in air
CO 0.07%
CH4 21 ppm
He 18 ppm
COS 18 ppm

Geologic Background. Momotombo is a young, 1297-m-high stratovolcano that rises prominently above the NW shore of Lake Managua, forming one of Nicaragua's most familiar landmarks. Momotombo began growing about 4500 years ago at the SE end of the Marrabios Range and consists of a somma from an older edifice that is surmounted by a symmetrical younger cone with a 150 x 250 m wide summit crater. Young lava flows from Momotombo have flowed down the NW flank into the 4-km-wide Monte Galán caldera. The youthful cone of Momotombito forms a 391-m-high island offshore in Lake Managua. Momotombo has a long record of strombolian eruptions, punctuated by occasional larger explosive activity. The latest eruption, in 1905, produced a lava flow that traveled from the summit to the lower NE base. A small black plume was seen above the crater after an April 10, 1996 earthquake, but later observations noted no significant changes in the crater. A major geothermal field is located on the southern flank of the volcano.

Information Contacts: H. DeLorme, Univ. de Paris; J. Cheminée, IPG, Paris.