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The 26 May 1982 breakout flows derived from failure of a volcanic dam at El Chichon, Chiapas, Mexico

J. L. Macias, L. Capra, K. M. Scott, J. M. Espindola, A. Garcia-Palomo and J. E. Costa
The 26 May 1982 breakout flows derived from failure of a volcanic dam at El Chichon, Chiapas, Mexico
Geological Society of America Bulletin (February 2004) 116 (1-2): 233-246


The eruptions of El Chichon between 28 March and 4 April 1982 produced a variety of pyroclastic deposits. The climactic phase, on 3 April at 07:35 (4 April at 01:35 GMT), destroyed the central andesitic dome and fed pyroclastic surges and flows that dammed nearby drainages, including the Magdalena River. By late April, a lake had formed, 4 km long and 300-400 m wide, containing a volume of 26X10 (super 6) m (super 3) of hot water. At 01:30 on 26 May, the pyroclastic dam was breached and surges of sediment and hot water soon inundated the town of Ostuacan, 10 km downstream. This hot flood was finally contained at Penitas Hydroelectric Dam, 35 km downstream, where one fatality occurred and three workers were badly scalded. Stratigraphic and sedimentologic evidence indicates that the rapidly draining lake initially discharged two debris flows, followed by five smaller debris flows and water surges. The main debris flows became diluted with distance, and by the time they reached Ostuacan, they merged into a single hyperconcentrated flow with a sediment concentration of approximately 30 vol%. Deposits from this hyperconcentrated flow were emplaced for 15 km, as far as the confluence with another river, the Mas-Pac, below which the flow was diluted to sediment-laden streamflow. The minimum volume of the breakout-flow deposits is estimated at 17X10 (super 6) m (super 3) . From high-water marks, flow profiles, and simulations utilizing the DAMBRK code from the National Weather Service, we calculated a maximum peak discharge of 11,000 m (super 3) /s at the breach; this maximum peak discharge occurred 1 h after initial breaching. The calculations indicated that approximately 2 h were required to drain the lake.

ISSN: 0016-7606
EISSN: 1943-2674
Serial Title: Geological Society of America Bulletin
Serial Volume: 116
Serial Issue: 1-2
Title: The 26 May 1982 breakout flows derived from failure of a volcanic dam at El Chichon, Chiapas, Mexico
Affiliation: Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Mexico City, Mexico
Pages: 233-246
Published: 200402
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 33
Accession Number: 2004-014656
Categories: Environmental geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 2 tables, geol. sketch map
N17°19'60" - N17°30'00", W93°19'60" - W93°10'00"
Secondary Affiliation: U. S. Geological Survey, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200405
Program Name: USGSOPNon-USGS publications with USGS authors
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