The eruption of the Nevado del Ruiz volcano on September 1, 1989. Geological data and model of the eruption
DOI:
https://doi.org/10.32685/0120-1425/bolgeol35.2-3.1995.292Keywords:
Colombia, phreatomagmatic eruption, lithic ash, juvenile ash, pumice
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Abstract
The eruption of September 1, 1989, of phreatomagmatic character, lasted 2 hours and 24 minutes, being preceded and followed by small phreatic eruptions of ashes. The main episode must have generated an eruptive column 8 km high but was subsequently controlled by the action of strong winds, which caused the tephras to be deposited in a range between N30ºW and S80ºW, reaching distances greater than 80 km in a straight line from the Nevado del Ruiz volcano.
The emitted material corresponds to lithic ash, juvenile ash, and pumice, with a calculated volume of more than 1 623 000 m3.
The erupted products are acid andesites to dacites, composed of plagioclase, pyroxenes and as accessories biotite and amphibole.
The eruption produced a small lahar, very similar to the phreatic eruption of September 11, 1985, destroying the concrete bridge that was on the road leading from Manizales (Caldas) to Murillo (Tolima); this lahar quickly lost its dragging capacity and stopped downstream without breaking the first cable of the mudflow monitor, located in the Azufrado River, which is located 7 km from the Arenas crater.
References
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