Popocatépetl: a deep dive into Mexico's smoking mountain
Popocatépetl is one of the most consequential active volcanoes on Earth, not because it has been spectacularly destructive in recent memory, but because of who lives in its shadow. Within a hundred kilometres of its 5,426-metre summit live nearly 25 million people, including those of Mexico City. The mountain has been continuously restless since 1994.
A glaciated stratovolcano on the Trans-Mexican Belt
Popocatépetl, "Popo," sits on the Trans-Mexican Volcanic Belt that crosses central Mexico from west to east. It is paired with its extinct neighbour Iztaccíhuatl, "Izta," a long ridge to the north that resembles a sleeping woman. Both rise above the Mexico City basin and are visible from the city on clear days.
A long volcanic history
The mountain has built itself in successive episodes over 730,000 years. Massive collapses in prehistoric times sent debris avalanches all the way to where Puebla now stands. Plinian eruptions in the ninth and fourteenth centuries deposited thick pumice and ash layers that archaeologists still find in cores around the basin.
The 1994 awakening
Popocatépetl had been quiet for about seventy years when, on 21 December 1994, an ash eruption restarted activity. Since then, the volcano has been more or less continuously active: a slowly building lava dome at the summit, periodic explosions that destroy it, and near-daily ash plumes drifting downwind.
Living in its shadow
The towns of Atlixco, Cholula and Amecameca sit close beneath the cone. Schools train evacuation drills; the Mexico City airport has contingency plans for ash on the runways. Most of the time, however, life proceeds as if the smoking summit were a backdrop, not a threat — because, mostly, it is.
The 2023 paroxysm
In May 2023 the mountain entered an unusually active phase, with several large explosions launching ash to 15 kilometres and forcing flight cancellations into and out of Puebla and Mexico City. The warning level rose to "yellow phase 3," the highest before mandatory evacuation. The phase eased without disaster, but it reset what authorities consider plausible.
The hiking ban
Until the late 1990s, Popo was a popular climb — one of the easier 5,000-metre objectives in North America. Since the eruption restart, the volcano has been closed to climbers. Hikers can still reach the Paso de Cortés saddle between Popo and Izta, where the view is unforgettable.
Monitoring
Mexico's National Centre for Disaster Prevention (CENAPRED) runs the Popocatépetl monitoring network — one of Latin America's most comprehensive, with seismometers, GPS, infrared cameras and SO₂ measurements. Forecasting daily activity has become routine; the challenge is communicating the rare possibility of a much larger event.
Why Popocatépetl matters
Popocatépetl matters because of geography. A modest VEI-3 eruption in the wrong wind closes Latin America's largest airport. A larger event would test the capacity of the world's third-largest urban area to evacuate millions on short notice. The continuous low-level activity is the most-watched dress rehearsal in volcanology.
On the map
Open the map and find Popocatépetl between Mexico City and Puebla. Iztaccíhuatl rises just to the north; further along the belt, Nevado de Toluca, La Malinche and the Pico de Orizaba mark the chain east.