It's been almost full month since my last post, but I'm back to it! In the beginning of December I flew out to
California for the annual American Geophysical Union Fall Meeting - a
week-long gathering of thousands of earth and space scientists in
downtown San Francisco. With
over 22,000 attendees and a huge range of topics, there's a ton of
exciting (and sometimes not so exciting) science on display at AGU. It's
impossible to give a full overview of everything I learned, but here
are a few research tidbits I found interesting.
Avalanches
Dr. Michaela Teich (WSL Institute for Snow and Avalanche Research SLF)
and coauthors are studying how forests influence avalanche flow in
order to improve predictive capabilities of avalanche models. Parameters
like tree type, tree height and tree spacing all affect the initial
triggering of an avalanche as well as the dynamics during a flow. Dr.
Teich has taken an empirical approach to calculate a detrainment
coefficient, a measure of how much snow mass is captured by a given
forest type. The detrainment coefficient can then be used in simulations
of avalanches to better predict flow paths and avalanche risk.
I find this problem particularly intriguing because of the differences
in scales involved - the ability of a forest to slow an avalanche
rushing down a mountainside depends on the characteristics of a forest,
which is influenced by the structure of individual trees. One of the
biggest challenges of theoretical research in the physical sciences is
understanding how to fit together processes that occur on different
spatial and temporal scales. So while it may not be possible to build an
avalanche simulation that includes individual trees, it may be possible
to include the affects of individual trees by considering how they
contribute to a forest's ability to capture snow. (Citation:
Teich et al., 2013 AGU Abstract C41B-0615, Evaluation and
operationalization of a novel forest detrainment modeling approach for
computational snow avalanche simulation)
Magma Migration
Dr. Wenlu Zhu (University of Maryland)
presented an overview of impressive experimental work being done to
constrain the permeability of partially molten rocks. When rocks melt in
the mantle, they only melt a little bit. That small amount of magma,
however, forms an interconnected network that allows the magma to
migrate upwards. As magma gets closer to the Earth's surface, the flow
localizes into increasingly larger pathways until finally collecting in
magma chambers that then erupt. So the permeability in the upper mantle
ultimately modulates how fast magma gets to surface and fuel volcanic
activity.
Besides the scientific merit, these experiments
are an impressive feat of engineering - Dr. Zhu and her students take
rock samples, bring them to high temperature and pressure so that they
melt a little bit and then shoot X-rays through them. Because magma has
different properties from solid rock, the X-rays can be used to map out
the magma network (here's a link to an image showing the magma network).
One of the more recent updates that Dr. Zhu showed, was work by
graduate student Kevin Miller in which he took the magma network and
input it to a fluid dynamics model in order to calculate the effective
permeability of the network. (citation: Zhu et al, 2013 AGU Abstract, MR23C-01. Permeability Evolution and the Mechanisms of Porosity Change)
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