Estimating the mass, volume, and dispersal of the deposits of very small and/or extremely weak explosive eruptions is difficult, unless they can be sampled on eruption. During explosive eruptions of Halema‘uma‘u Crater (Kîlauea, Hawaii) in 2008, we constrained for the first time deposits of bulk volumes as small as 9-300 m³ (1 × 10⁴ to 8 × 10⁵ kg) and can demonstrate that they show simple exponential thinning with distance from the vent. There is no simple fit for such products within classifications such as the Volcanic Explosivity Index (VEI). The VEI is being increasingly used as the measure of magnitude of explosive eruptions, and as an input for both hazard modeling and forecasting of atmospheric dispersal of tephra. The 2008 deposits demonstrate a problem for the use of the VEI, as originally defined, which classifies small, yet ballistic producing, explosive eruptions at Kîlauea and other basaltic volcanoes as nonexplosive. We suggest a simple change to extend the scale in a fashion inclusive of such very small deposits, and to make the VEI more consistent with other magnitude scales such as the Richter scale for earthquakes. Eruptions of this magnitude constitute a significant risk at Kîlauea and elsewhere because of their high frequency and the growing number of "volcano tourists" visiting basaltic volcanoes.

Item Type:	Refereed Article
Keywords:	Bulk volume, explosive eruption, hazard modeling, Kilauea, magnitude scale, non explosives, Richter scale, Volcanic Explosivity Indices
Research Division:	Earth Sciences
Research Group:	Geology
Research Field:	Volcanology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the earth sciences
UTAS Author:	Carey, RJ (Associate Professor Rebecca Carey)
ID Code:	84673
Year Published:	2013
Web of Science® Times Cited:	42
Deposited By:	Earth Sciences
Deposited On:	2013-05-24
Last Modified:	2017-11-02
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