Causes of supervolcano eruptions
Abstract
Large explosive eruptions commonly form caldera depressions and emit hundreds to thousands of cubic kilometres of silicic magma. They have profound local, regional, and global impacts. Despite the significance of these eruptions, little is known about the conditions under which large caldera-forming eruptions occur, in particular the underlying causes, the driving mechanisms, and the trigger or triggers. To address these issues, we have undertaken a series of analogue experiments and numerical calculations designed to elucidate linkages among subsurface magma behaviour, caldera collapse dynamics, and large volcanic eruptions. Here we show that five complementary prerequisites are required to generate and sustain a supervolcano eruption. (1) Recharge by mafic and/or silicic magma into a shallow reservoir destabilizes the system, generates overpressure, and partially melts resident crystallized magma. (2) A quantity of low-viscosity liquid magma must be present in the reservoir prior to the eruption, either as resident material or from recharge magma and partial melting. (3) Once the eruption is initiated, this mobile magma flows at high rates to the surface, inducing catastrophic caldera collapse. (4) A shallow magma reservoir facilitates caldera collapse during early stages of the eruption. (5) Subsidence of the caldera stirs and mixes magma in the conduits and reservoir, causing focused flow of magma which can potentially intensify the eruption. These five conditions ensure that a caldera-forming eruption will be large and sustained.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.V21G..05S
- Keywords:
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- 8414 VOLCANOLOGY / Eruption mechanisms and flow emplacement;
- 8434 VOLCANOLOGY / Magma migration and fragmentation;
- 8439 VOLCANOLOGY / Physics and chemistry of magma bodies;
- 8440 VOLCANOLOGY / Calderas