OFFICIALS are preparing to evacuate tens of thousands of people from around a
volcano near Mexico City that is threatening to blow its top.
For the first time, volcanologists have pieced together a map of which
settlements are most at risk from lava and mudflows following an eruption. Some
people could have less than an hour to get out before being overwhelmed.
Popocat茅petl or 鈥淧opo鈥� as the mountain is colloquially known, has been
relatively quiet for the past 1200 years. That changed last December, when
people in the nearby city of Amecameca became alarmed by unusual amounts of
smoke and ash coming from the crater. With lava now welling up in the crater,
geologist Michael Sheridan of the University of Buffalo in New York says there
is a 30 per cent chance that there could soon be an eruption.
Advertisement
Sheridan joined a team of scientists from the National Autonomous University
of Mexico (UNAM) in Mexico City to map the path molten rock would take if Popo
does blow, as well as mudflows caused by glaciers melting in the heat of an
eruption.
The team created a computer model based on data from mudflows and ash
deposits of past volcanic eruptions. When they overlaid their results with a map
of population density near Popo, they found nearly 100,000 people to be at risk
from a major eruption (see Graphic).
Sheridan says he is particularly concerned about people living on the south
side of the volcano. Many only speak the Aztec language N谩hautl, making
it harder for Spanish-speaking officials to organise an evacuation.
Using the map as a guide, officials at the National Centre for Disaster
Prevention (Cenapred) in Mexico City are beginning to plan evacuation routes.
They are monitoring the volcano so they can raise the alarm if it begins to
bulge鈥攁 sign that an eruption is imminent.
Carlos Valdes of Cenapred says the computer model is helpful for forecasting
which towns will be affected by eruptions of different sizes. Cenapred鈥檚
interest is a positive step, says Claus Siebe at UNAM. 鈥淣ormally civil
authorities are rather reactive, there鈥檚 not much prevention,鈥� he says. But the
eruption of the Colombian volcano Nevado del Ruiz in 1985, which killed tens of
thousands of people in the city of Armero, has concentrated the minds of many in
Latin America. 鈥淲e鈥檙e remembering what happened in Armero,鈥� says Valdes. 鈥淲e鈥檙e
looking very carefully.鈥�