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Report on Michoacan-Guanajuato (Mexico) — December 1989

Scientific Event Alert Network Bulletin, vol. 14, no. 12 (December 1989)
Managing Editor: Lindsay McClelland.

Michoacan-Guanajuato (Mexico) Fumarole temperatures decrease

Please cite this report as:

Global Volcanism Program, 1989. Report on Michoacan-Guanajuato (Mexico). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 14:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198912-341060.

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19.85°N, 101.75°W; summit elev. 3860 m

All times are local (unless otherwise noted)

Geologists visited Ahuan fumarole on 23 November. The fumarole temperature was 305°C, a decrease from 336°C measured in May 1988.

Geologic Background. The widespread Michoacán-Guanajuato volcanic field contains over 1400 vents, including the historically active cinder cones of Parícutin and Jorullo, covering a 200 x 250 km wide area of Michoacán and Guanajuato states in west-central México. Cinder cones are the predominant volcanic form, but small shield volcanoes, lava domes, maars and tuff rings (many in the Valle de Santiago area), and coneless lava flows are also present. The shield volcanoes are mostly Pleistocene in age, and have morphologies similar to small Icelandic-type shield volcanoes, although the Michoacán-Guanajuato shields have higher slope angles and smaller basal diameters. Jorullo, which was constructed in the 18th century, and Parícutin, which grew above a former cornfield during 1943-52, are the two best known of the roughly 1000 small volcanic centers scattered throughout the volcanic field.

Information Contacts: Kurt Roggensack, Helen Mango, John Lucio, and Half Zantop, Dartmouth College.