Mexico’s active Popocatepetl volcano prompts alerts, school closures

A severe eruption from the volcano, located 72 kilometers southeast of Mexico City, could cut off air traffic or smother the city in clouds of choking ash.

Mexico’s Popocatepetl volcano rumbled to life again this week, belching out towering clouds of ash that forced 11 villages to cancel school sessions.

The residents weren’t the only ones keeping a close eye on the towering peak. Every time there is a sigh, tic or heave in Popocatepetl, there are dozens of scientists, a network of sensors and cameras, and a roomful of powerful equipment watching its every move.

The 5,426-meter volcano, known affectionately as “El Popo,” has been spewing toxic fumes, ash and lumps of incandescent rock persistently for almost 30 years, since it awakened from a long slumber in 1994.

The volcano is 72 kilometers southeast of Mexico City, but looms much closer to the eastern fringes of the metropolitan area of 22 million people. The city also faces threats from earthquakes and sinking soil, but the volcano is the most visible potential danger — and the most closely watched. A severe eruption could cut off air traffic, or smother the city in clouds of choking ash.

Ringed around its summit are six cameras, a thermal imaging device and 12 seismological monitoring stations that operate 24 hours a day, all reporting back to an equipment-filled command center in Mexico City.

A total of 13 scientists from a multidisciplinary team take turns staffing the command center around the clock. Being able to warn of an impending ash cloud is key, because people can take precautions. Unlike earthquakes, warning times can be longer for the volcano and in general the peak is more predictable.

On a recent day, researcher Paulino Alonso made the rounds, checking the readings at the command center run by Mexico’s National Disaster Prevention Center, known by its initials as Cenapred. It is a complex task that involves seismographs that measure the volcano’s internal trembling, which could indicate hot rock and gas moving up the vents in the peak.

Monitoring gases in nearby springs and at the peak — and wind patterns that help determine where the ash could be blown — also play a role.