(pronounced: PO-po-kah-TAY-pet-uhl) is part of the Trans-Mexican Volcanic Belt, a series of east-west trending stratovolcanoes that reaches across southern Mexico from Jalisco to Veracruz.
Like many subduction-related volcanoes, Popocatépetl is a stratovolcano, and typically erupts dacitic and andesitic material. Gas emissions are very common, and Popocatépetl is one of the world's largest producers of sulfur dioxide (Goff et al., 1998). Recent research into the petrology and geochemistry at Popocatepetl suggest that the current eruptive activity (1994-present) is the result of a basaltic andesite magma mixing into a chamber of more silicic magma (Witter et al., 2005).

The name "Popocatépetl" comes from the Aztec civilizations who inhabited the region before European contact in the 15th century, and means "smoking mountain." The volcano has been active for about the last 15,000 years (Delgado-Granados et al., 2001), and its activity has been documented in the oral history of indigenous civilizations. Archeological artifacts found in mudflow and ash deposits suggest that of Popocatépetl since ~3200 BCE repeatedly destroyed several ancient villages in the region (Siebe et al., 1996).

Present day activity at Popocatépetl has primarily consisted of degassing and ash eruptions that create small  columns viewable from Mexico City and the surrounding countryside. Though no major cities lie within the immediate hazard area, Mexico City (population 8.8 million) is only 70km away, and many other settlements ranging from small agricultural villages to large urban centers are close enough that they would be severely endangered by a Plinian eruption. Activity is heavily monitored by the Centro Nacional de Prevencion de Desastres (National Center for the Prevention of Disasters).

Despite the threats that Popocatépetl poses to humans in the region, it also offers opportunities -- volcanic ash deposits from past eruptions create rich soils, and the volcano itself (as well as neighboring volcano Iztaccihuatl) are located in a national park that attracts thousands of tourists to the area every year.