♦Spectral lahar detection♦

Participant: Lucia Capra, Norma Davila, Gianluca Norini, Francesco Zucca.
Financial support:PAPIIT-UNAM (IN103107 to LC)

We used LIDAR topographic coverage, ASTER and LANDSAT images for the recognition of morphological changes in the drainage system and lahar detection. For lahar delineation we applied principal components analysis and canonical classification (Tasseled Cap) in order to perform a supervised image classification using the maximum likelihood rule algorithm.

Supervised classification of the Colima volcano. Note that lahars can be distinguished in the dark-blue color from the pyroclastic flow deposit as red-light green.

From top to bottom: principal components of the VNIR spectrum of the 2001 and 2006 ASTER images (as RGB combination). Note that lahars are easily recognizable in an orange tone. In the insets, two fans on San Antonio and Montegrande ravines are compared. ©Lucia Capra

♦Triggering mechanism of lahars♦

Participant: Lucia Capra, Borselli Lorenzo, Damiano Sarocchi, Juan Carlos Gavilanes-Ruiz, Nick Varley, Gianluca Norini.
Financial support:PAPIIT-UNAM (IN103107 to LC)

Based on the analisys between lahar frequency and rain intensity, the mechanism of lahar initiation is analyzed. Textural characteristics of source material are determined to understand infiltration proceses and the generation of overland flows.

Diagram showing the rainfall characteristic of some tipical events and the occurence of some lahars events. ©Lucia Capra

From upper left, and in a clockwise sense: Picture showing the limits of watershed that feed main ravines. A "lahar" fall on the Montegrande ravine (© V. Vargas). Lahar on San Antonio ravine (© F. Ziemen and J. Stevenson). Alluvial fan at the end of the Montegrande ravine where several lahars deposit large clasts. ©Lucia Capra

♦Lahar hazard delineation♦

Participant: Lucia Capra, Juan Carlos Gavilanes, Gianluca Norini, Norma Davila, Nick Varley.
Financial support:PAPIIT-UNAM (IN103107 to LC) CONACYT (46340 to LC)

LAHARZ has been used and tested using two topographic datasets with different resolutions, which provided evidence of the importance of high-resolution topographic coverage in hazard assessment. Inundation limits where simulated using maximum volums of 500,000 m³.

Hazard map for high frequency and low magnitude lahars at Volcán de Colima. Note that several small villages can be affected by such type of flow. ©Lucia Capra

Photos showing the several examples of damages provoked by lahars. a), b) and c) Aerial view of the 1999 lahar in the Montegrande ravine where electric lines have been destroyed, note that the electric lines are now protected by a small rock barrier. d) and e) Bridge over La Lumbre ravine where lahars charged with metric-sized blocks partially damaged the structure. ©Lucia Capra

♦Volcano instability of Colima Volcano: Causes and triggering mechanisms ♦

Participant: Lucia Capra, Matteo Roverato, Gianluca Norini, Abel Cortes, Roberto Sulpizio.
Financial support:PAPIIT-UNAM (IN103107 to LC)

Previous authors determined that the Colima Volcanic Complex has suffered at least nine flank collapses during the past 22,000 years. The main objective of this project is to perform a detailed stratigraphic study of debris avalanche deposits with particular attention to the associated pyroclastic sequences to better understand the dynamic of the eruption. Analogue modeling will be used to determine how the regional and local tectonic setting is controlling the direction of the collapse.

Vertical cross section of a deformed analogue cone cut perpendicular to the basal shear showing deformation and intrusion ©Gianluca Norini

Debris avalanche deposit that outcrops at Montegrande ravine. ©Lucia Capra

Cohesive debris flow in the Naranjo River. ©Lucia Capra