The cohesive Naranjo debris-flow deposit (10 km 3):
Mass movement processes on volcanic terrains such as landslides and debris avalanches can cause the obstruction of main drainages producing the formation of temporary dams. A good example of this occurred 18.5 ka ago when the eastern flank of the Nevado de Colima Volcano collapsed producing a debris-avalanche deposit that was previously described as one of the largest in the world. The deposit extended from the volcanic summit as far as the Pacific coast, 120 km away. New stratigraphic, sedimentological, and componentry data suggest that the volcanic collapse of Nevado de Colima resulted in a debris avalanche that traveled 20 km southeast to the Naranjo River. There it crashed against a topographic barrier consisting of Cretaceous limestones (Cerro la Carbonera) and the flow direction was diverted to the south down the Naranjo River channel for another 25 km before the avalanche came to a halt. The obstruction of the drainage produced a temporary dam that stored ca. 1 km3 of water and deposited fluvial and slack-water sediments. Some time after the damming, the accumulated water-sediment load was able to overtop the obstructing material and to release a breakout flow with a calculated initial flow discharge of 3.5 million m3/s. The resulting flood (cohesive debris flow) followed the channel of the Naranjo River and, due to the high erodibility of the channel and introduction of substrate material, the debris flow progressively increased its volume up to 10 km3, six times its initial volume. This study highlights the relevance of evaluating the potential remobilization of debris-avalanche deposits to initiate large magnitude cohesive debris flows. Therefore, the hazard and risk analysis of future potential events of this nature must consider the pre-eruption conditions and the topography surrounding a volcano. 7 2002 Elsevier Science B.V. All rights reserved.
Holocene evolution of the Colima Volcanic Complex, Mexico
Current activity at the Colima Volcanic Complex (CVC) is characterised by the andesitic lava dome growth and small Vulcanian style eruptions of Volcan de Colima; however, road cuts on the nearby Nevado de Colima, reveal a record of explosive eruptions spanning the Holocene and Late Pleistocene. New data presented here, in combination with published and unpublished datasets, reveal the majority of tephra fallout deposits spanning the last ~13,000 years, are medium-K sub-alkaline, ranging in composition from basaltic-andesite to high-silica andesite (50.7 - 60.4 wt.% SiO2). These magmas display typical subduction-related trace element signatures with enriched fluid mobile elements (Rb, Ba, La, Ce, Sr) relative to high field strength elements (i.e. Nb, Ta). 
Three units interbedded in the CVC stratigraphy, erupted at c.7000, 12,000 and 13,000 years before present (yrs B.P.), reveal pulses of alkaline magmatism which intersect the magmatic storage region of the CVC on timescales of thousands of years. These units are mineralogically and geochemically distinct from the typical sub-alkaline eruption deposits, characterised by the presence of phlogopite and elevated K2O, P2O5 and incompatible trace element abundances. Through two-component mixing models, using whole-rock major and trace element geochemical data, and Sr-Nd isotopic data, after Langmuir et al. (1978), the alkaline component within these mixed magmas has been quantified to between 20 and 70%. 
A new model defining the nature of the magmatic plumbing system of the CVC is presented, drawing on previously published models for alkaline magma petrogenesis, recent geophysical studies, and new petrological and geochemical data. Mineral compositions and textures reveal multiple phases of growth and destabilisation interpreted to reflect decompression and magma recharge events consistent with multiple levels of magma storage within the crust below the CVC. 
Finally, initial volume estimates based on tephra modelling reveal these explosive eruptions were subplinian (0.03 to 0.3km3) events. These initial results reveal a link between magma composition and eruption volume, with the most evolved CVC magmas producing large volume eruptions.
Landsat Thematic Mapper observations of debris avalanche deposits in the Central Andes
Remote sensing studies of the Central Andean volcanic province between 18°–27°S with the Landsat Thematic Mapper have revealed the presence of 28 previously undescribed breached volcanic cones and 14 major volcanic debris avalanche deposits, of which only 3 had previously been identified. Several of the debris avalanche deposits cover areas in excess of 100 km2 and have volumes of the order of 10 km3. H/L ratios for the deposits have a median of 0.1 and a mean of 0.11, values similar to those determined for deposits described in other regions. Surface morphologies commonly include the hummocky topography of small hillocks and enclosed basins that is typical of avalanche deposits, but some examples exhibit smoother surfaces characterised by longitudinal grooves and ridges. These differences may result from the effects of flow confinement by topography or from variations in resistance to shearing in the materials involved. Breached composite cones and debris avalanche deposits tend to occur at right angles to regional tectonic elements, suggesting possible seismic involvement in triggering collapse and providing an additional consideration for assessment of areas at risk from collapse. The low denudation rate in the Central Andes, coupled with the predominance of viscous dacite lavas in volcanic edifices, produces unusually steep cones which may result in a higher incidence of volcano collapse than in other regions. A statistical survey of 578 composite volcanoes in the study area indicates that a majority of cones which achieve edifice heights between 2000–3000 m may undergo sector collapse.