Universidad de Colima reported that as of 23 March volcanism continued at Colima and more small explosion earthquakes were recorded than during the previous week. Incandescent lava avalanches, generated from the fronts of block-lava flows, continued to travel 2-3 km down Colima's S, SW, and W flanks, and also sporadically traveled down the volcano's E flank. Block-lava flows extended 550 m down the SW flank and 2 km down the W flank. Based on information from the Mexico City MWO, the Washington VAAC reported that on 25 March at 1040 a steam-and-ash emission rose ~5-6 km a.s.l. and drifted to the E. The 6.5-km-radius exclusion zone around Colima remained in effect, with other restrictions to access out to 11.5 km from the volcano's summit.

Geological Summary. The Colima complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the high point of the complex) on the north and the historically active Volcán de Colima at the south. A group of late-Pleistocene cinder cones is located on the floor of the Colima graben west and east of the complex. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide scarp, breached to the south, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, producing thick debris-avalanche deposits on three sides of the complex. Frequent recorded eruptions date back to the 16th century. Occasional major explosive eruptions have destroyed the summit (most recently in 1913) and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth.

Sources: Centro Universitario de Estudios e Investigaciones de Vulcanologia - Universidad de Colima, Washington Volcanic Ash Advisory Center (VAAC)