Publication Date:
2017-04-04
Description:
Accepted for publication in (Geophysical Research Letters). Copyright (2009) American Geophysical Union.
Description:
It is currently impractical to measure what happens in a volcano during an explosive eruption,
and up to now much of our knowledge depends on theoretical models. Here we show, by means of
large-scale experiments, that the regime of explosive events can be constrained based on the
characteristics of magma at the point of fragmentation and conduit geometry. Our model, whose
results are consistent with the literature, is a simple tool for defining the conditions at conduit exit
that control the most hazardous volcanic regimes. Besides the well-known convective plume
regime, which generates pyroclastic fallout, and the vertically collapsing column regime, which
leads to pyroclastic flows, we introduce an additional regime of radially expanding columns, which
form when the eruptive gas-particle mixture exits from the vent at overpressure with respect to
atmosphere. As a consequence of the radial expansion, a dilute collapse occurs, which favours the
formation of density currents resembling natural base surges. We conclude that a quantitative
knowledge of magma fragmentation, i.e. particle size, fragmentation energy and fragmentation
speed, is critical for determining the eruption regime.
Description:
Research was partially funded by DPC-INGV agreement 07-09 and MUR PRIN 06
Description:
In press
Description:
1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
Description:
JCR Journal
Description:
open
Keywords:
explosive eruptions
;
04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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