Publication Date:
2017-04-04
Description:
Lava dome eruptions are commonly characterized by
large fluctuations in discharge rate with cyclic behaviour on
time-scales ranging from hours to decades. Examples include
Bezymianny volcano (Russia), Merapi (Java), Santiaguito
(Guatemala), Mt St Helens (USA), Mt Unzen (Japan), and
Soufrie`re Hills volcano (Montserrat). Previous models have
assumed simple cylindrical conduits for magma transport,
but extrusions are mainly fed by dykes, with cylindrical
geometries developing only at shallow levels. The widths of
dykes embedded in an elastic medium are influenced by local
magma pressure, affecting flow rates and system dynamics
strongly. We develop a model for magma flow in dykes,
which predicts intense pulsations of magma extrusion for the
case of a constant source pressure. The period time scale is
determined by the elastic deformation of the dyke walls and
the length-to-width ratio of the dyke. The dyke acts like a
volumetric capacitor, storing magma as pressure increases
and then releasing magma in a pulse of extrusion. For the
Soufrie`re Hills volcano, cyclic extrusions with time-scales of
a few weeks are predicted for dykes 300–500 m long and
3–6 m wide, matching observations. The model explains
the sharp onset of tilt pulsations and seismic swarms.
Description:
Published
Description:
L02303
Description:
3.6. Fisica del vulcanismo
Description:
JCR Journal
Description:
reserved
Keywords:
Control
;
magma flow
;
dykes
;
cyclic lava
;
04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
;
04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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