Nov. 25, 1998 BUFFALO, N.Y. -- The eruption of Colima volcano -- also known as Volcan del Fuego, or "Volcano of Fire" -- that began on Nov. 20 has produced its first pyroclastic flows that could signal the start of the volcano's most dangerous period since its catastrophic eruption in 1913, a University at Buffalo volcanologist says.
Michael F. Sheridan, Ph.D., professor and chair of the UB Department of Geology and a co-author of the current hazards map of Colima, says that while activity at the volcano may continue in "fits and starts," the weak condition of the volcano summit, combined with the weight of lava that is now emerging, has created an extremely unstable situation.
Two nearby villages, Yerba Buena and Juan Baragan, were evacuated last week.
In Spring 1991, computer simulations developed by Sheridan accurately predicted the course and magnitude of pyroclastic avalanches from Colima that occurred shortly afterward.
Last month, at the annual meeting of the Geological Society of America, Sheridan reported that extremely fast-moving volcanic mudflows could inundate and destroy a large part of a key industrial town located northeast of Colima sometime within the next 10 years.
That would be the case, he says, only if a major explosion should occur as a result of pent-up pressure at the volcano's summit, and if a blanket of volcanic ash from the volcano was mobilized by torrential rains, which could come next spring or earlier.
"While there is still considerable uncertainty whether the current activity is a prelude to a major event, all of the precursors, such as the lava emission at the summit and the formation of pyroclastic flows, have already occurred," Sheridan says.
There is fresh magma at the summit and the slope is very steep, he adds.
"As magma surges upward, the volcano swells and unstable slopes begin to crumble and slide, becoming avalanches," he says. "This mixture of older, cool lava and new, red-hot magma can become fluidized and cascade down the volcano's sides at speeds of 100 miles per hour or more."
According to Sheridan, this could produce incandescent dust clouds so thick that people caught in them can die from severe burns or suffocation.
He adds that Colima currently is emitting 4,000 tons of sulfur per day, enough to produce a significant cooling effect on the global climate if the eruption continues.
A pioneer in developing computerized simulations of volcanoes that allow researchers to estimate how fast and how far ash flows from an eruption will travel, Sheridan has been honored by the University of Colima for his scientific work on the activity of the volcano and for his training of young Mexican scientists at UB and elsewhere.
The most dangerous volcano in Mexico, Colima has erupted violently three times during the past 450 years. About 2,300 years ago, it produced a cataclysmic avalanche much larger than that of Mount St. Helens in 1980.
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