Mexican authorities have raised the alert level at the Popocatépetl volcano after smoke, ash and lava spewed into the sky.
The volcano, located in central Mexico, is considered one of the world’s most dangerous as about 25 million people live within a ten-mile radius of it.
Sunday’s increased alert level – to “yellow phase three” – comes a day after two airports in Mexico City temporarily halted operations due to falling ash.
In case of yellow warning phase three, people are asked to be prepared for possible evacuation. The alert level is triggered when “explosions of increasing intensity, ejecting glowing fragments” emanate from the volcano.
The next step, a red alert, means mandatory evacuation.
A large number of shelters have already been opened in areas around the volcano.
Popocatépetl, which on clear days can be seen from the capital Mexico City, has not had any massive eruptions for more than a millennium, but since 1994 it has had several periods of increased activity.
