Thousands of people living in the shadow of this looming Mexican volcano have been placed on high alert following a dramatic increase in seismic activity from the Popocatepetl crater.

The 17,886ft active volcano near Mexico City, known as Popo, rumbled and shook during the night on Saturday, and has been spewing ash, lava and steam in recent days.

Officials have closed off an exclusion zone around the cone of the volcano and are poised to evacuate towns in its foothills as experts warned of plumes of steam reaching more than half a mile into the sky above the crater.

Authorities have alerted town in two central states as well as the capital, after Mexico’s National Disaster Prevention Center elevated its alert level to Yellow Phase 3 – the fifth rung on a seven-stage warning scale.
Should the alert level rise thousands of people could be evacuated from the most vulnerable villages in the shadow of the peak. Shelters have been set up in case authorities are forced to evacuate residents.

Popocatepetl is an Aztec word meaning ‘Smoking Mountain’. Popo lay dormant for decades until it began putting out small eruptions of ash almost daily in 1994. These eruptions started strengthening two weeks ago and have increased even more this weekend.

The millions of people who have settled in and around the Mexican capital mean experts regard Popocatepetl as one of the most potentially destructive volcanoes in the world.