MEXICO - Volcano Rattles Nerves

"Volcano Puts Mexico on Alert" by JEAN GUERRERO, Wall Street Journal 4/20/2012

The towering Popocatépetl volcano outside Mexico City rumbled loudly and spewed plumes of ash, water vapor and hot rocks high into the sky on Friday, scaring nearby residents and putting Mexican officials on alert.

Mexican President Felipe Calderón visited nearby communities and flew close to the crater Friday morning, later calling on residents via his Twitter account to prepare in case of a needed evacuation by keeping at hand a battery-powered radio, flashlight, medicine and important documents.

"It is important to keep calm," Mr. Calderón wrote. "We are closely watching the activity of Popocatépetl."

Authorities mapped out evacuation routes, and prepared shelters in case the volcano's activity increases.

Experts say a massive eruption of the 17,886-foot (5,450-meter) volcano is unlikely, but a buildup of a magma chamber under its slopes may release clouds of thick ash that could blanket Mexico City and cause havoc at its international airport.

"Popo," as the volcano is affectionately known in Mexico, came back to life in 1994 after decades of relative quiet and regularly emits puffs of ash and vapor. In fact, the volcano's name in Mexico's indigenous Nahuatl language means "smoking mountain."

In the past week, the volcano's activity suddenly increased, forcing authorities to raise the alert level and place a seven-mile security radius around the mountain, which sits 35 miles outside of the capital.

Overnight on Friday, the volcano emitted a deep roar that could be heard for miles and spooked residents. Experts say the volcano's emissions have been particularly frightening to nearby residents at night because they give the false impression of being lava.

"The material has a certain temperature that makes it look incandescent at night, and that is why you see the red," said Juan Carlos Mora Chaparro, a volcanologist at the Geophysics Institute of the National Autonomous University of Mexico. However, he said that unlike lava, the materials being emitted are cool by the time they reach the ground.

Mr. Mora said it is impossible to know how far the effect of a potential volcanic eruption would reach at this point, but that it could destroy areas many kilometers away.