Large ignimbrite eruptions and volcano-tectonic depressions in the Central Andes: A thermomechanical perspective
Published:January 01, 2006
Shanaka De Silva, George Zandt, Robert Trumbull, José G. Viramonte, Guido Salas, Néstor Jiménez, 2006. "Large ignimbrite eruptions and volcano-tectonic depressions in the Central Andes: A thermomechanical perspective", Mechanisms of Activity and Unrest at Large Calderas, C. Troise, G. De Natale, C. R. J Kilburn
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The Neogene ignimbrite flare-up of the Altiplano Puna Volcanic Complex (APVC) of the Central Andes produced one of the best-preserved large silicic volcanic fields on Earth. At least 15 000 km3 of magma erupted as regional-scale ignimbrites between 10 and 1 Ma, from large complex calderas that are typical volcano-tectonic depressions (VTD). Simple Valles-type calderas are absent. Integration of field, geochronological, petrological, geochemical and geophysical data from the APVC within the geodynamic context of the Central Andes suggests a scenario where elevated mantle power input, subsequent crustal melting and assimilation, and development of a crustal-scale intrusive complex lead...
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Mechanisms of Activity and Unrest at Large Calderas
Large caldera collapses represent catastrophic natural events, second only to large meteoritic impacts. In addition, some calderas are densely populated, making the risk extreme, even for moderate eruptions. Understanding caldera mechanisms, unrest and the danger of eruption is therefore a crucial challenge for Earth sciences.
Several key features of caldera behaviour have yet to be fully understood. Through a combination of case studies and theoretical modelling, the following topics are addressed in this volume: the conditions required to produce and to release large volumes of magma erupted during caldera formation; how magmatic feeding systems evolve before and after a caldera has formed; the processes that limit the behaviour of precursors to eruptions; how pre-emptive precursors can be distinguished from those that drive unrest without an eruption; and given that post-collapse eruptions may occur across a wide area, the optimum procedures for designing hazard maps and mitigation strategies.