We discuss and comment on the role agriculture will play in the containment of the CO2 problem and address protocols for terraforming the planet Earth.
A model farm template is imagined as the central methodology. A broad range of timely science news and other topics of interest are commented on.
Tuesday, February 5, 2013
New Type of Volcanic Eruption
The outflow is buoyant but not explosive. This could well make sense
of a lot of geology that presumes explosive eruptions yet generates
huge deep flows of materials over a large area. When you consider
it, we have no evidence of deep explosive sub sea events anywhere
close to what we experience on land. They must then behave
differently and this shows us how.
It is quite right to attach a fresh name to this type of volcano.
It also suggests that during the sub sea stage, most of the material
will accumulate close to hand and help build the cone that does
eventually break surface. It may even be a low faster than we
actually expect. I the meantime, we think that they are rare, but
they may be merely invisable.
Scientists based in
the UK and New Zealand have described a "new" type of
volcanic eruption. Volcanic eruptions are commonly categorised as
either explosive or effusive. But now, in research published this
month in Nature Geoscience, researchers at Victoria University,
Wellington and the National Oceanography Centre in Southampton have
uncovered a previously undocumented type of eruption in underwater
volcanoes - by looking at tiny original bubble spaces trapped in
gases are dissolved in the molten magma as a function of the very
high pressures and chemistry of the magma. In the same way that gases
dissolved in carbonated drinks bubble up when you take the lid off,
when magma is erupted as lava, the pressure is relieved and the gases
exsolve to form small gas bubbles or so-called "vesicles".
In explosive eruptions
these vesicles expand so quickly they fragment the magma, violently
ejecting lava, which cools and degasses to form solidified pumice
that can be sufficiently light to float on water.
In air pumice is
obviously associated with violent, explosive eruptions. Consequently
underwater volcanoes flanked by highly vesicular pumice have, to
date, also been interpreted as having erupted explosively.
But the results of
this study indicate that there is a third eruptive style unique to
underwater volcanoes, which is neither effusive nor explosive.
the shape and density of bubbles in pumices generated by an
underwater caldera volcano in the southwest Pacific Ocean - the
Macauley volcano - we found large differences in the number and shape
of "bubbles" in the same pebble-sized samples, different to
anything previously documented," said Professor Ian Wright of
the National Oceanography Centre, who co-authored the paper.
"This range of
bubble densities distinct in these pumice samples indicates that the
lava erupting from the caldera was neither vigorous enough for an
explosive eruption, nor gentle enough for an effusive flow."
The study proposes
that rather than exploding in the neck of the volcano, the
formation and expansion of bubbles in the magma created a buoyant
foam, which rose to the seafloor and then buoyantly detached from the
volcano as molten pumice balloons but with chilled margins.
During its ascent to the sea surface, the vesicles within the molten
interior would have continued to expand as the pressure - this time
from the weight of the seawater – reduced.
explain the unique bubble structure seen in the samples analysed,
which could have only occurred with an intermediate eruption style
and in an underwater setting," said Professor Wright.
"We conclude that
the presence of widespread deposits of pumice on underwater volcanoes
does not necessarily indicate large-scale explosive volcanism."
The authors proposed
that this style of eruption be named Tangaroan, the Maori god of the
sea, and name of the research vessel used to collect the samples.
The study was led by
Melissa Rotella, Professor Colin Wilson and Simon Barker from the
School of Geography, Environment and Earth Sciences at the Victoria
University of Wellington, New Zealand. The paper referred to is:
Rotella M. D., Wilson C. J. N., Barker S. J. and Wright I. C. (2013)
Highly vesicular pumice generated by buoyant detachment of magma in
subaqueous volcanism. Nature Geoscience doi: 10.1038/NGEO1709.