Pigeonholing pyroclasts: Insights from the 19 March 2008 explosive eruption of Kīlauea volcano

Geology
By: , and 

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Abstract

We think, conventionally, of volcanic explosive eruptions as being triggered in one of two ways: by release and expansion of volatiles dissolved in the ejected magma (magmatic explosions) or by transfer of heat from magma into an external source of water (phreatic or phreatomagmatic explosions). We document here an event where neither magma nor an external water source was involved in explosive activity at Kīlauea. Instead, the eruption was powered by the expansion of decoupled magmatic volatiles released from deeper magma, which was not ejected by the eruption, and the trigger was a collapse of near-surface wall rocks that then momentarily blocked that volatile flux. Mapping of the advected fall deposit a day after this eruption has highlighted the difficulty of constraining deposit edges from unobserved or prehistoric eruptions of all magnitudes. Our results suggest that the dispersal area of advected fall deposits could be miscalculated by up to 30% of the total, raising issues for accurate hazard zoning and assessment. Eruptions of this type challenge existing classification schemes for pyroclastic deposits and explosive eruptions and, in the past, have probably been interpreted as phreatic explosions, where the eruptive mechanism has been assumed to involve flashing of groundwater to steam.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Pigeonholing pyroclasts: Insights from the 19 March 2008 explosive eruption of Kīlauea volcano
Series title Geology
DOI 10.1130/G31509.1
Volume 39
Issue 3
Year Published 2011
Language English
Publisher Geological Society of America
Contributing office(s) Volcano Science Center
Description 4 p.
First page 263
Last page 266
Country United States
State Hawaii
Other Geospatial Kilauea Volcano
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
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