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Report on San Cristobal (Nicaragua) — July 1981

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

San Cristobal (Nicaragua) Medium- to high-temperature gases collected

Please cite this report as:

Global Volcanism Program, 1981. Report on San Cristobal (Nicaragua). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 6:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198107-344020.

Volcano Profile |  Complete Bulletin


San Cristobal

Nicaragua

12.702°N, 87.004°W; summit elev. 1745 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 gases from five central American volcanoes. Medium- to high-temperature gases from San Cristóbal were analyzed (table 1). Maximum gas temperatures measured were 525°C.

Table 1. Analytical mean of three mid-1981 gas samples (dry, HCl excluded) from San Cristóbal.

[Skip text table]
    Component    Mean Value

    SO2            65.40%
    CO2            33.93%
    H2              0.31%
    H2S             0.33%
    N2              4.35% in air
    CO              0.02%
    CH4            65 ppm
    He             12 ppm
    COS            27 ppm

Geologic Background. The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1745-m-high youngest cone, named San Cristóbal (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km W of San Cristóbal; it and the eroded Moyotepe volcano, 4 km NE of San Cristóbal, are of Pleistocene age. Volcán Casita, containing an elongated summit crater, lies immediately east of San Cristóbal and was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes.

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