Report on Michoacan-Guanajuato (Mexico) — November 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 11 (November 1986)
Managing Editor: Lindsay McClelland..
Michoacan-Guanajuato (Mexico) Temperature of hottest fumarole declines; HCl-rich gases
Please cite this report as:
Global Volcanism Program, 1986. Report on Michoacan-Guanajuato (Mexico). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 11:11. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198611-341060.
19.85°N, 101.75°W; summit elev. 3860 m
All times are local (unless otherwise noted)
When geologists visited Parícutin 26 November, fumaroles were emitting HCl-dominated gases. The temperature of Ahuan fumarole (on the SW flank) was 375°C, about 100° lower than in November 1985. Other fumaroles remained at about 100°C. No other changes were observed.
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: R. Stoiber, C. Connor, and other geologists, Dartmouth College.