Major Volcanoes of the World

Colima

Colima's Volcano is the most active volcano in Mexico, and has erupted more than 40 times since 1576.
Despite its name, only a fraction of the volcano's surface area is contained within the state of Colima; the majority of its surface area lies just over the border in the neighboring state of Jalisco, toward the western end of the Eje Volcánico Transversal mountain range. It is about 300 miles (485 kilometres) west of Mexico City and 75 miles (125 km) south of Guadalajara, Jalisco.
There are actually two peaks in the volcano complex: Nevado de Colima (4330 metres), which is older and inactive, lies about 5 kilometres north of the younger and very active 3860 metre Volcán de Colima (also called Volcán de Fuego de Colima). Since 1869-1878, a parasitic set of domes, collectively known as El Volcancito, have formed on the northeast flank of the main cone of Colima's volcano .

Geological history
Colima's volcano has been active for about 5 million years. In the late Pleistocene era, a huge landslide occurred at the mountain, with approximately 25 km³ of debris travelling some 120 km, reaching the Pacific Ocean. An area of some 2,200 km² was covered in landslide deposits. Massive collapse events seem to recur at Colima's volcano every few thousand years.
The currently active cone is situated within a large caldera that was probably formed by a combination of landslides and large eruptions. About 300,000 people live within 40 km of the volcano, and in light of its history of large eruptions and situation in a densely populated area, it has been designated a Decade Volcano, singling it out for particular study.