I probably am the envy of quite a few fifth graders I’ve I’ve got a big
fifth graders I’ve I’ve got a big
fifth graders I’ve I’ve got a big laboratory I work for the Smithsonian
laboratory I work for the Smithsonian
laboratory I work for the Smithsonian Institution I get to play with lasers I
Institution I get to play with lasers I
Institution I get to play with lasers I study volcanoes so that we can have a
study volcanoes so that we can have a
study volcanoes so that we can have a better understanding of why eruptions
better understanding of why eruptions
better understanding of why eruptions happen and then when an eruption does
happen and then when an eruption does
happen and then when an eruption does happen why does it behave the way that
happen why does it behave the way that
happen why does it behave the way that it does volcanologists describe volcanic
it does volcanologists describe volcanic
it does volcanologists describe volcanic rocks as lavas which erupt and flow out
rocks as lavas which erupt and flow out
rocks as lavas which erupt and flow out across the surface and then there’s
across the surface and then there’s
across the surface and then there’s pyroclastic rocks a natural prior
pyroclastic rocks a natural prior
pyroclastic rocks a natural prior plastic flow are ups from volcano as a
plastic flow are ups from volcano as a
plastic flow are ups from volcano as a mixture of pumice and ash and gas that
mixture of pumice and ash and gas that
mixture of pumice and ash and gas that explodes upward as a cloud and then
explodes upward as a cloud and then
explodes upward as a cloud and then collapses to make a current in our case
collapses to make a current in our case
collapses to make a current in our case we heat up talc powder we load them onto
we heat up talc powder we load them onto
we heat up talc powder we load them onto a conveyor belt and then we slowly pour
a conveyor belt and then we slowly pour
a conveyor belt and then we slowly pour them into the tank at a controlled rate
them into the tank at a controlled rate
them into the tank at a controlled rate that powder that we introduce flows out
that powder that we introduce flows out
that powder that we introduce flows out across the base of the current as a
across the base of the current as a
across the base of the current as a cloud and that cloud is essentially the
cloud and that cloud is essentially the
cloud and that cloud is essentially the pyroclastic flow that we’re simulating
so one of the challenges of
so one of the challenges of understanding what’s going on on a
understanding what’s going on on a
understanding what’s going on on a pyroclastic flow is being able to see
pyroclastic flow is being able to see
pyroclastic flow is being able to see the interior of that flow and in a
the interior of that flow and in a
the interior of that flow and in a natural current you really only see the
natural current you really only see the
natural current you really only see the the outer surface of the cloud in our
the outer surface of the cloud in our
the outer surface of the cloud in our experiments we can see right through the
experiments we can see right through the
experiments we can see right through the cloud and so what we use is some lasers
cloud and so what we use is some lasers
cloud and so what we use is some lasers to illuminate essentially a single slice
to illuminate essentially a single slice
to illuminate essentially a single slice through the current we can see the laser
through the current we can see the laser
through the current we can see the laser sheets are going to be using to
sheets are going to be using to
sheets are going to be using to illuminate the currents and we use here
illuminate the currents and we use here
illuminate the currents and we use here we have three laser sheets we have a
we have three laser sheets we have a
we have three laser sheets we have a green laser sheet this horizontal and is
green laser sheet this horizontal and is
green laser sheet this horizontal and is about five centimeters above the floor
about five centimeters above the floor
about five centimeters above the floor we have a blue laser sheet that runs the
we have a blue laser sheet that runs the
we have a blue laser sheet that runs the length of the tank and is vertical then
length of the tank and is vertical then
length of the tank and is vertical then we have a red laser sheet that runs
we have a red laser sheet that runs
we have a red laser sheet that runs across the tank and is also vertical and
across the tank and is also vertical and
across the tank and is also vertical and these three sheets between them give us
these three sheets between them give us
these three sheets between them give us an idea of the 3d structure of these
an idea of the 3d structure of these
an idea of the 3d structure of these pyroclastic flows one of the surprises
pyroclastic flows one of the surprises
pyroclastic flows one of the surprises that we’ve had with these experiments is
that we’ve had with these experiments is
that we’ve had with these experiments is that there are some enormous differences
that there are some enormous differences
that there are some enormous differences in the behavior of cold currents versus
in the behavior of cold currents versus
in the behavior of cold currents versus warm currents if we look at how a cold
warm currents if we look at how a cold
warm currents if we look at how a cold current spreads out across the floor it
current spreads out across the floor it
current spreads out across the floor it spreads out more or less radially
spreads out more or less radially
spreads out more or less radially if instead we put a hot current into the
if instead we put a hot current into the
if instead we put a hot current into the tank it initially starts out as a
tank it initially starts out as a
tank it initially starts out as a somewhat radial but then very quickly
somewhat radial but then very quickly
somewhat radial but then very quickly becomes a very long narrow current and
becomes a very long narrow current and
becomes a very long narrow current and we think this is because as the current
we think this is because as the current
we think this is because as the current lifts off that upward motion of the
lifts off that upward motion of the
lifts off that upward motion of the plume basically prevents any further
plume basically prevents any further
plume basically prevents any further spread of the current to the sides one
spread of the current to the sides one
spread of the current to the sides one of the other surprises we’ve had is that
of the other surprises we’ve had is that
of the other surprises we’ve had is that when currents encounter a barrier or a
when currents encounter a barrier or a
when currents encounter a barrier or a topographic Ridge the currents if
topographic Ridge the currents if
topographic Ridge the currents if they’re warm they hit that barrier and
they’re warm they hit that barrier and
they’re warm they hit that barrier and they lift off to form a plume and they
they lift off to form a plume and they
they lift off to form a plume and they really don’t keep going at all volcanoes
really don’t keep going at all volcanoes
really don’t keep going at all volcanoes can inject ash up into the stratosphere
can inject ash up into the stratosphere
can inject ash up into the stratosphere they can shutdown aviation over a large
they can shutdown aviation over a large
they can shutdown aviation over a large fraction of the globe they can also
fraction of the globe they can also
fraction of the globe they can also influence the climate so having a better
influence the climate so having a better
influence the climate so having a better understanding of how volcanoes work can
understanding of how volcanoes work can
understanding of how volcanoes work can hopefully help us mitigate some of those
hopefully help us mitigate some of those
hopefully help us mitigate some of those volcanic hazards
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