The following report is from the Centro de Investigación en Ciencias Básicas. "On 14 February at 0800, RESCO detected an increase in seismic activity, clearly associated with Colima volcano. From a baseline of a few tectonic events/day (high-frequency - A-type) to two events/hour of volcanic origin (low-frequency - B-type), seismic activity increased continuously [over the next several hours] until it reached five B-type events/hour. RESCO registered approximately 106 earthquakes between 1150 on 14 February and 1000 on 15 February. This activity diminished markedly after a M 3.5 earthquake at 1705 on 14 February.

"On 16 February, RESCO operators working at Nevado de Colima, the older summit 5 km N of the active cone, observed two rockfall avalanches on the W flank of the volcano, at 1245 and 1315, respectively. Fumarole emissions were dense and white in color, but approximately every 20 minutes, these emissions were accompanied by others with a strong dark gray color." No ashfalls were reported.

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.

Information Contacts: Guillermo Castellanos, Gilberto Ornelas-Arciniega, C. Ariel Ramírez-Vázquez, G.A. Reyes-Dávila, Hector Tamez, and Francisco Núñez-Cornú, CICBAS, Universidad de Colima; A. Nava, Z. Jiménez, and S. de la Cruz-Reyna, UNAM; C. Connor, FIU, Miami.