A Peruvian city of a million people named on Monday as being at high risk from a volcanic explosion has no emergency plan and continues to allow building on the lower slopes of the volcano, New Scientist has discovered.
El Misti towers above the second city of Peru, Arequipa. French volcanologist Jean Claude Thouret says its potential impact “is as worrisome as that of Vesuvius near Naples”.
In 2000, Thouret, from the Université Blaise-Pascal in Clermont-Ferrand, provided Arequipa’s planners with detailed maps of possible lava flows and rock falls from an eruption. But when New Scientist visited the city in November 2001, the authorities professed ignorance of the threat.
“We don’t have a plan for El Misti,” said the head of civil defence in southern Peru, Carlos Nacarino Rodriguez. And the mayor of the poor Arequipa suburb of Alto Selva Alegre, Lucio Candia Ramirez, claimed that “scientists have found no problem with El Misti. We do see smoke from it sometimes, but it is soon gone”. Alto Selva Alegre is built in the bed of a ravine that would carry lava into the city.
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“Impending threat”
On Monday Thouret published the first detailed geological survey of El Misti. There have been five minor eruptions this century. But the last major eruption occurred in the 15th century, when rocks rained down for several weeks and forced residents to flee.
With layers of ash occurring in the geological record every 500 to 1500 years, Thouret says another eruption is an “impending threat”.
He fears explosions “that could cover the city”, lava flows that might engulf a third of the population, and flash floods from melting snow and breached reservoirs. The volcano is also on a major fault line through Peru, giving credence to local fears that 2001’s earthquake in the region could trigger a new eruption.
In recent years, the city has spread to within 13 kilometres of the summit. Nonetheless, Thouret told New Scientist, “the civil defence people see it as a remote danger, and the city authorities did not respond to my suggestion of avoiding development on the volcano side of the city.”
He says his foreboding about El Misti stems from the first volcano he studied, Nevado del Ruiz in Colombia. It erupted in 1985, before he could finish his thesis, killing 23,000 people.
Journal reference: Geological Society of America Bulletin (vol 113, p 1593)
