Publication Date:
2017-04-04
Description:
The FLOWGO thermo-rheological model links heat loss, core cooling, crystallization,
rheology and flow dynamics for lava flowing in a channel. We fit this model to laser
altimeter (LIDAR) derived channel width data, as well as effusion rate and flow
velocity measurements, to produce a best-fit prediction of thermal and rheological
conditions for lava flowing in a ~1.6 km long channel active on Mt. Etna (Italy) on 16th
September 2004. Using, as a starting condition for the model, the mean channel width
over the first 100 m (6 m) and a depth of 1 m we obtain an initial velocity and
instantaneous effusion rate of 0.3-0.6 m/s and ~3 m3/s, respectively. This compares
with field- and LIDAR-derived values of 0.4 m/s and 1-4 m3/s. The best-fit between
model-output and LIDIR-measured channel widths comes from a hybrid run in which
the proximal section of the channel is characterised by poorly insulated flow and the
medial-distal section by well-insulated flow. This best-fit model implies that flow conditions evolve down-channel, where hot crusts on a free flowing channel maximise
heat losses across the proximal section, whereas thick, stable, mature crusts of 'a'a
clinker reduce heat losses across the medial-distal section. This results in core cooling
per unit distance that decreases from ~0.02-0.015 °C m-1 across the proximal section, to
~0.005 °C m-1 across the medial-distal section. This produces an increase in core
viscosity from ~3800 Pa s at the vent to ~8000 Pa s across the distal section.
Description:
In press
Description:
open
Keywords:
lava flow
;
thermo-rheological
;
04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article