15 years of lahar monitoring at Volcán de Colima, Mexico: insights on triggering mechanisms, flow characteristics and hazards assessment.
Lucia Capra 1, Víctor Márquez Ramirez1, Raúl Arámbula-Mendoza2, Miguel González Maezcua2, Rogelio García Flores2
Affiliations: 1 Instituto de Geociencias, UNAM, Mexico 2 Centro Universitario de Estudios e Investigaciones de Vulcanología, Universidad de Colima, México
Presentation type: Talk [Invited]
Presentation time: Tuesday 10:30 - 10:45, Room R280
Programme No: 3.5.1
Abstract
The Volcán de Colima, Mexico, is a natural laboratory for studying lahars, including their initiation mechanisms, downflow behavior, and associated hazards. A comprehensive monitoring system incorporating seismic, visual, and rainfall data was established in 2010 and now covers lahar detection along four ravines. Morphology surveys using drones have also been implemented. Real-time monitoring at Volcán de Colima has enabled the seismic classification of lahars based on their magnitude and sediment concentration, characteristics linked to the watershed morphology of each ravine and the rainfall intensity-duration. On the upper volcano slopes, progressive sediment entrainment promotes the transition from hyperconcentrated flows to debris flows, characterized by the succession of surges with block-rich fronts. In the middle and distal reaches, the channel morphology highly controls bulking and debulking processes, responsible for lahar downflow variation in magnitude and sediment concentration. The 2015 eruption deposited over 7 million cubic meters of pyroclastic material into the Montegrande ravine which, since then, recorded up to 40 lahars per year during the rainy season. Based on morphological survey, an erosion rate of up to 105 cubic meters per year has been estimated. In contrast, along other ravines, unaffected by pyroclastic deposition during the last 20 years, lahars are generated only during exceptional rainfall events, with sediments primarily sourced from material accumulated at the foot of the terrace wall due to minor landslides. These findings have advanced lahar detection and hazard assessment at Volcán de Colima, enhancing understanding of sediment dynamics and flow behavior.