HR: 1400h
AN: V23A-08    [Abstracts]
TI: Costa Rica's Chain of laterally collapsed volcanoes.
AU: * Duarte, E
EM: eduarte@una.ac.cr
AF: OVSICORI-UNA Costa Rica, Campus Universidad Nacional , Heredia, Her 3000, Costa Rica
AU: Fernandez, E
EM: efernan@una.ac.cr
AF: OVSICORI-UNA Costa Rica, Campus Universidad Nacional , Heredia, Her 3000, Costa Rica
AB: From the NW extreme to the SW end of Costa Rica's volcanic backbone, a number of laterally collapsed volcanoes can be observed. Due to several factors, attention has been given to active volcanoes disregarding the importance of collapsed features in terms of assessing volcanic hazards for future generations around inhabited volcanoes. In several cases the typical horseshoe shape amphitheater-like depression can be easily observed. In other cases due to erosion, vegetation, topography, seismic activity or drastic weather such characteristics are not easily recognized. In the order mentioned above appear: Orosi-Cacao, Miravalles, Platanar, Congo, Von Frantzius, Cacho Negro and Turrialba volcanoes. Due to limited studies on these structures it is unknown if sector collapse occurred in one or several phases. Furthermore, in the few studied cases no evidence has been found to relate collapses to actual eruptive episodes. Detailed studies on the deposits and materials composing dome-like shapes will shed light on unsolved questions about petrological and chemical composition. Volume, form and distance traveled by deposits are part of the questions surrounding most of these collapsed volcanoes. Although most of these mentioned structures are extinct, at least Irazú volcano (active volcano) has faced partial lateral collapses recently. It did presented strombolian activity in the early 60s. Collapse scars show on the NW flank show important mass removal in historic and prehistoric times. Moreover, in 1994 a minor hydrothermal explosion provoked the weakening of a deeply altered wall that holds a crater lake (150m diameter, 2.6x106 ). A poster will depict images of the collapsed volcanoes named above with mayor descriptive characteristics. It will also focus on the importance of deeper studies to assess the collapse potential of Irazú volcano with related consequences. Finally, this initiative will invite researchers interested in such topic to join future studies in these Costarrican volcanoes.
UR: http:www.ovsicori.una.ac.cr
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8425 Effusive volcanism
DE: 8428 Explosive volcanism
DE: 8488 Volcanic hazards and risks
DE: 8499 General or miscellaneous
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly