Abrams, M., Glaze, L., and Sheridan, M.F., 1991, Monitoring Colima Volcano, México, using satellite data. Bulletin of Volcanology, 53:571-574.

Stoopes, G.R. and Sheridan, M.F., 1992, Giant debris avalanches from the Colima volcanic Complex, México: Implications for long-runout landslides (>100 km). Geology, 20:299-302.

Martin del Pozzo, A. L., Sheridan, M.F., 1993, Vulcan de Colima, Geofisica Internacional, 32(4):541-542. (editors of special volume on Colima)

Sheridan, M.F. and Macías, J.L, 1995, Estimation of risk probability for gravity-driven pyroclastic flows at Volcán Colima, México. Journal Volcanology and Geothermal Research, 66:251-256.

Martin del Pozzo, A. L., Sheridan, M.F., Barrera, D., Hubp, J.L, and Selem, L.V., 1995, Potential Hazards from Colima Volcano, México. Geofisica Internacional, 34:363-376.

Martin del Pozzo, A. L., Sheridan, M.F., Barrera, D., Hubp, J.L, and Selem, L.V., 1995,  Mapa de Peligros Volcán de Colima, Instituto de Geofisica, UNAM, México.

Geological Society of America, Toronto, October 1998

ESTIMATED LAHAR HAZARD ZONES AT VOLCAN COLIMA, MEXICO

 PAUL, Yvonne and SHERIDAN, Michael F., Department of Geology, SUNY at Buffalo, Buffalo, NY 14260; mfs@acsu.buffalo.edu

Volcan Colima is a decade volcano and the most active volcano in Mexico. Currently it is approaching its climactic phase and a major eruption could occur in the next decade. Volcanic debris flows are likely to occur in the two major drainages to the east and west of the volcano, Rio Tuxpan and Rio Armeria respectively. Theoretical lahar inundation zones have been computed using a model developed by Iverson and others (1998) for the Cascade Range. Lahar volumes of 4 magnitudes (10⁵ to 10⁸ m³) were tested in the river valleys. The peak flow width and depth were calculated at intervals of a few km along the channels and the runout lengths computed. Lahars of all magnitudes studied will stay within the main valleys of the two rivers. One town in particular, Atenquique, is at high risk for lahars of all scales because it is near the volcano and at the bottom of a deep canyon. The largest lahars (10⁸ m³) would have a peak depth of about 60 m and a runout of about 120 m, reaching the sea. The smallest lahars examined (10⁵ m³) would have a peak height of about 7 m and would only reach about 15 km distance. These models should be helpful for risk planning at Volcan Colima.

American Geophysical Union, San Francisco, December 1999

HAZARD ZONES DEMARKING INUNDATION LIMITS FOR DEBRIS FLOWS AND DEBRIS AVALANCHES AT VOLCAN COLIMA, MEXICO

SHERIDAN, Michael F., HUBBARD, Bernard, and HOOPER, Donald, Department of Geology, SUNY at Buffalo, Buffalo, NY 14260; mfs@acsu.buffalo.edu, ABRAMS, Michael, Jet Propulsion Laboratory, Pasadena, California

Volcan Colima, the most active volcano in Mexico, is approaching the climactic phase of its eruptive cycle. Eruptions in 1998-99 produced numerous pyroclastic flows to the south and southwest and fine volcanic ash deposited northeast of the volcano. The repose period between its four historic catastrophic episodes is about 100 years suggesting that a major explosion is eminent. In the more distant past huge volcanic debris flows with a recurrence interval of between 2,000 and 4,000 years resulted from repeated edifice collapse. The probability of structural failure should be higher during a major explosive episode, suggesting that this type of event cannot be an excluded scenario. Simulations for hazard assessment were made on a Defense Mapping Agency DEM with a 90-m grid and a vertical accuracy of ± 30 m. Volcanic debris avalanches, modeled using FLOW3D and a Heim coefficient of 0.09, correspond fairly well to the spatial distribution of mapped past avalanche deposits. All debris flows, regardless of source type, eventually move down one of the two major river systems, Rio Tuxpan to the east and Rio Armeria to the west. Present river valleys cut into volcanic debris avalanche deposits as young as 2,300 years. The formation of terraces within these river channels is compatible with passage of debris flows with magnitudes in the range of those modeled. Assuming likely source areas in ash fall, pyroclastic flow, and volcanic avalanche deposits, inundation zones for lahar volumes of three magnitudes (10⁶ to 10⁸ m³) were simulated with ArcInfo using the LAHARZ model developed by Iverson and others (1998). Their GIS code calculates flow cross sectional areas to plot the width of the peak flow in the river valleys and uses planimetric area to map the flow extent. Mudflows of all studied magnitudes remain within the principal valleys of the two rivers. The largest studied debris flows have a runout of 37 to 51 km, but the smallest flows reach only 3 to 4 km from their source. Unfortunately, a large lumber-producing town, Atenquique, is at high risk for moderate to large lahars because it is near the volcano and at the bottom of a deep canyon. At this location the hydraulic radius of the largest model lahars (10⁸ m³) would be about 75 m and that of the intermediate flows (10⁷ m³) would be about 40 m. Atenquique would be inundated by such mudflows.

American Association of Geographers, Pittsburgh, April 2000

USE OF GIS TO OUTLINE  HAZARD ZONES FOR LARGE DEBRIS FLOW INUNDATION AT VOLCAN COLIMA, MEXICO

SHERIDAN, Michael F., HUBBARD, Bernard, and HOOPER, Donald, Department of Geology, SUNY at Buffalo, Buffalo, NY 14260; mfs@acsu.buffalo.edu, ABRAMS, Michael, Jet Propulsion Laboratory, Pasadena, California

Volcan Colima, historically the most active volcano in Mexico, is approaching the climactic phase of its 100-year cycle; a major explosion is eminent. Eruptions in the past year spread increasing amounts of fine volcanic ash around the volcano, enhancing the potential for volcanic mudflows. Assuming that source areas for debris flows would be located in zones where accumulation of new volcanic ash is thickest, mudflows are most likely to move down two major river systems, Rio Tuxpan to the east and Rio Armeria to the west. Inundation zones for lahar volumes of 3 magnitudes (10⁶ to 10⁸ m³) were simulated with ArcInfo using the LAHARZ model developed by Iverson and others (1998). Their GIS code calculates flow cross sectional areas to plot the width of the peak flow in the river valleys and uses planimetric area to map the flow extent. Mudflows of all studied magnitudes remain within the principal valleys of the two rivers. The largest studied debris flows have a runout of 37 to 51 km but the smallest flows reach only 3 to 4 km from their source. Unfortunately, a large lumber-producing town, Atenquique, is at high risk for moderate to large lahars because it is near the volcano and at the bottom of a deep canyon. At this location the hydraulic radius of the largest lahars (10⁸ m³) would be about 75 m and that of the intermediate flows (10⁶ m³) would be about 40 m. Atenquique would be devastated by such mudflows.