Report on Colima (Mexico) — 8 July-14 July 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 8 July-14 July 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Colima (Mexico). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 8 July-14 July 2015. Smithsonian Institution and US Geological Survey.
19.514°N, 103.62°W; summit elev. 3850 m
All times are local (unless otherwise noted)
In a 7 July bulletin, the Unidad Estatal de Protección Civil de Colima reported that during the previous week explosions from a fast-growing lava dome at Colima generated ash plumes that rose 3 km above the crater. Incandescent rock avalanches, from explosions and the lava dome overtopping the crater rim, descended the flanks. Ashfall was reported in various communities downwind. The report warned the public not to enter an area within a 5-km radius of the crater, and to avoid drainages within 14 km due to lahar hazards. La Coordinación Nacional de Protección Civil reported that during 7-10 July a gradual increase in the number of emissions and landslides was detected. Pyroclastic flows traveled at most 2.5 km down the N, W, and S flanks. During 9-10 July incandescent material was ejected from the crater.
Based on satellite images and webcam views, the Washington VAAC reported an intense thermal anomaly and constant ash emissions on 10 July. A large event at 1200 produced an ash plume that rose to an altitude of 7.6 km (25,000 ft) a.s.l. and drifted 150 km W. La Coordinación Nacional de Protección Civil noted that activity further increased at 2017 on 10 July, characterized by incandescent material descending the WSW flanks, pyroclastic flows, and ash plumes that rose 4 km above the crater. Ash fell in the communities of La Yerbabuena (5-cm-thick ash deposits), La Becerrera (88 SW), San Antonio, Carrizalillo, El Naranjal, Nuevo Naranjal, and Suchitlán (18 km SSW) in Colima State. The Unidad Estatal de Protección Civil de Colima ordered 19 residents in La Yerbabuena to evacuate, and some residents in nearby towns self-evacuated. A pyroclastic flow traveled 9 km S. By 1030 on 11 July there were 70 confirmed evacuees in shelters. Citing large eruptions in the past, La Coordinación Nacional de Protección Civil enforced a preventative evacuation within 12 km of the crater. Ashfall was reported in Comala, Villa de Alvarez, and Colima. An additional 70 people had evacuated, and the national airport, El Aeropuerto Nacional de Colima, suspended operations due to ashfall. Ejected incandescent material, ash emissions, incandescent landslides, and pyroclastic flows continued at a moderate level during 11-12 July. Evacuations continued on 12 July, and ashfall persisted in Comala, Villa de Alvarez, and Colima. The report noted that La Unidad Estatal de Protección Civil and Bomberos de Jalisco continued to monitor the towns of Lomas de las Flores and San José del Carmen, and the municipality of Zapotitlán de Vadillo because they were the areas most affected by ashfall.
Geologic Background. The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4320 m high point of the complex) on the north and the 3850-m-high historically active Volcán de Colima at the south. A group of cinder cones of late-Pleistocene age is located on the floor of the Colima graben west and east of the Colima complex. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, 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, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth.