Popocatépetl also known as "Popochowa" by the local population is an active volcano and, at 5,426 m (17,802 ft), the second highest peak in Mexico after the Pico de Orizaba (5,636 m/18,491 ft).
The stratovolcano contains a steep-walled, 400 × 600 m (1,300 × 2,000 ft) wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris avalanche deposits covering broad areas south of the volcano. The modern volcano was constructed to the south of the late-Pleistocene to Holocene El Fraile cone. Three major plinian eruptions, the most recent of which took place about 800 CE, have occurred from Popocatépetl since the mid Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano.
Popocatepetl is one of the most violent volcanoes in Mexico, having had more than 15 major eruptions since the arrival of the Spanish in 1519. A major eruption occurred in 1947 to begin this cycle of activity. Then, on December 21, 1994, the volcano spewed gas and ash which was carried as far as 25 km (16 mi) away by prevailing winds. The activity prompted the evacuation of nearby towns and scientists to begin monitoring for an eruption. In December 2000, tens of thousands of people were evacuated by the government based on the warnings of scientists. The volcano then made its largest display in 1,200 years.Popocatepetl sends a plume of volcanic ash south on January 23, 2001, with Iztaccíhuatl at right. View from the International Space Station.
According to paleomagnetic studies, the volcano is about 730,000 years old. Elevation 5,450 m (17,880 ft) in cone form with a diameter of 25 km (16 mi) at its base and the crater has an elliptical shape with an orientation northeast-southeast. the walls of the crater oscillate between 600 to 840 m (2,000 to 2,760 ft). Popocatépetl is currently active after being dormant for about half of last century. In 1991 the volcano's activity increased and since 1993 smoke can be seen constantly emanating from the crater.
There is a large record of the volcano's activity throughout antiquity. In 1927 an eruption was artificially triggered by the use of dynamite in the crater for sulfur extraction. The last violent eruption was registered in 2000. On December 25, 2005, the volcano's crater produced a new explosion which ejected a large column of smoke and ash about 3 km (1.9 mi) into the atmosphere and expulsion of lava.
In late January and February of 2012, scientists have been noticing Popocatepetl's action increasing. On January 25, 2012, an ash explosion occurred on the mountain causing much dust and ash to contaminate the atmosphere around it.
The first Spanish ascent of the volcano was made by an expedition led by Diego de Ordaz in 1519. The early 16th-century monasteries on the slopes of the mountain are a World Heritage Site.