Title: Explosive Volcanic Activity Generated from Within Advancing Silicic Lava Flows
Abstract: After initial explosive activity, eruptions of silicic magma often decrease in violence and associated hazards due to a state of gentle degassing during effusion. Recent field mapping, microscopic, and geochemical analyses of drill core samples from the Inyo and Valles Scientific Drilling Programs indicate that during the advance of some silicic lava flows the concentration of volatiles may increase substantially, due to the migration and concentration of water vapor released by crystal growth and microfracturing. As a result, the explosive hazards related to emplacement of silicic lava flows may become greater rather than less as flow length increases, even though the overall volatile content of the extrusion is constant or decreasing. This idea is supported by the occurrence of explosion craters on the distal surfaces of large rhyolite flows, and by observations of nuées ardentes generated through the collapse of dacite lava flow fronts several kilometers from their vents. Volatile migration may also be responsible for the rise of diapirs of dark pumiceous lava to the flow surface. Hence, monitoring the surface appearance of an active silicic lava flow may provide indications of the potential for endogenic explosive activity.
Publication Year: 1989
Publication Date: 1989-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
Access and Citation
Cited By Count: 22
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