by Simon Tomlinson Daily Mail
The white-capped volcano that looms over Mexico City emitted a terrifying low-pitched roar this morning spewing ash and steam as it vented the pressure built up by a massive chamber of magma.
As a result authorities have now prepared evacuation routes, ambulances and shelters in the event of a bigger explosion.
Even a large eruption of the 17,886-foot cone of Popocatepetl is unlikely to do more than dump ash on one of the world’s largest metropolitan areas. But the grit could play havoc with Mexico City’s busy airport, and tens of thousands of people in the farming villages on its flanks could be forced to flee.
Popo, as it’s commonly known, has put out small eruptions of ash almost daily since a round of eruptive activity began in 1994.
A week ago, however, the eruptions started growing larger and authorities elevated the alert level for people living nearby.
Before dawn on Friday, the mountain moved into what appeared to be a new level of activity, spitting out dozens of ash clouds and fragments of glowing rock down its slopes while frightening the residents of surrounding villages with deep roaring not heard in a decade.
People in the village of Xalitzintla said they were awakened by a window-rattling series of eruptions.
Mexico’s National Disaster Prevention Center said one string of eruptions ended in the early morning, then the volcano started up again at 5:05am, with at least 12 eruptions in two hours.
‘Up on the mountain, it feels incredible,’ said Aaron Sanchez Ocelotl, 45, who was in his turf grass fields when the eruptions happened. ‘It sounds like the roaring of the sea.’
According to Roberto Quaas, director of the disaster prevention center, a 35 million cubic foot chamber of magma is seething about six miles beneath Popocatepetl.
Scientists have no way of predicting whether the molten rock in the chamber will be slowly released, or erupt in a powerful explosion like one on December 18, 2000, that sent up a plume of red-hot rock and forced the evacuation of thousands of people who live at the volcano’s base, Quaas said.
He compared the volcano to a bottle of champagne: ‘You could take the cork out quickly and all the gaseous material and liquid rushes out suddenly, or it could also happen slowly.
‘We know that this lava dome, sooner or later, will be destroyed by internal pressure.’
Scientists have detected fracturing about 3.5 miles down, accompanied by small earthquakes measuring about 3.4 magnitude, he said.
An iconic backdrop to Mexico City’s skyline on clear days, Popocatepetl sits roughly halfway between Mexico City and the city of Puebla – meaning some 25 million people live within a 60-mile radius of the volcano, Quaas said.
‘These are figures that obviously alarm and concern us,’ he said.
President Felipe Calderon and the governors of Mexico, Puebla and Morelos states that neighbor Popocatepetl said on a live national television broadcast that they were keeping roads open around the mountain, preparing emergency shelters and making sure residents know the latest information about a potential eruption.