A convecting ash column roils above a small, but impressive-looking pyroclastic flow from Colima volcano in Mexico on April 16, 1991. The pyroclastic flow, colored by the late-afternoon sun, was produced by collapse of unstable portions of the summit lava dome. It descended the SW flank but caused no damage to inhabited areas.
Collapse of Mexico's Colima volcanic complex during the late Pleistocene produced a major debris avalanche and debris flow that traveled 120 km from Nevado de Colima volcano to the Pacific Ocean. The quarried hummock in the foreground and the two brown hills in the middle distance are formed both of debris transported more than 100 km from Colima volcano (seen in the far distance above the lefthand hummock) and material from valley floors incorporated during transport.
Textures associated with volcanic landslides are preserved in this quarry wall more than 100 km from the source of a major avalanche from México's Colima volcano. Large fractured blocks appear at the top of the exposure, and a color mottling is produced by adjacent segments of the volcano or valley floor material incorporated during transport that are fractured, but not thoroughly mixed. A 2-m-high measuring rule provides scale.
The course of the block-lava flow in the foreground, which was emplaced during the 1975-76 eruption of Mexico's Colima volcano, can be seen descending through the vegetation at the center. The flow originated from the summit dome of Colima and traveled 3.5 km down the SE flank. The flow bifurcated on the upper slopes, forming another lobe that traveled to the east, forming the darker area that descends into the vegetation at the upper right.
A steam plume blows from the summit of México's Colima volcano in this 1992 view from the WSW with snow-capped Nevado de Colima to the left. Colima, also known as Fuego de Colima, is one of North America's most active volcanoes. Frequent eruptions have been recorded since the 16th century. A complex succession of eruptions that has been dominated during the past century by lava effusion associated with lava dome growth has also produced explosive eruptions of varying magnitude and frequent pyroclastic flows.