Episode Transcript
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Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works, Hi brain
Stuff Lauren Vogelbaum here. When Alaska's Pavlof volcano erupted in
March of it ejected a cloud of ash four hundred
miles or six d forty KOs high. The stream of sharp,
powdered rocks shut down air travel and major highways. Then
twice in May and July, the U S Geological Survey
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raised the alert level for pavlov which seemed ready to
do it again, but then they downgraded it in August.
Volcanic eruptions are notoriously unpredictable. Hans Lechner, a doctorial candidate
in geology and engineering sciences at Michigan Technological University, says
volcanologists haven't figured out the timing yet. He wrote via email,
a volcano may show all the signs of an impending eruption,
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increased seismicity, high gas flux, surface deformation, but then never
actually erupt and over time returned back to baseline levels.
Or he says, it can show none of the signs
of an impending eruption and then erupt. There are those
in the field who muse about going on the offensive.
The volcanic preemptive strike if you will. The idea is
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humans somehow modify the eruption process, either by initiating an
eruption under controlled conditions, or by downgrading the energy of
an impending eruption to limit the resulting damage. The energy
involved in a volcanic eruption defies the imagination. Italy's infamous
Mount Etna spewed about three cubic feet that's ten cubic
meters of lava per second during its four month eruption.
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In Lechno reports that in Mount Pinatubo's initial blast ejected
about two point four cubic miles or ten cubic kilometers
of material to an altitude of about twenty five miles
or forty kilometers. He says that magma represents massive amounts
of energy. It originates deep inside the Earth, where extreme
temperatures and pressures can melt rock. Molten rock or magma
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is lighter than solid rock, so it rises, forming a
magma chamber that moves upward through Earth's crust. As the
volume of magma grows, the pressure in the chamber increases,
forcing magma through the volcanoes vents tubes formed by prior
eruptions sealed at the surface by a lid of rock.
If the pressure gets high enough and Events suddenly opens
to the atmosphere, the rapid depressurization causes gases to come
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out of solution, which causes the magma to explode. It
spews through the open vents, along with pulverized rock, steam,
and various gases. In the case of Mount Saint Helen's
in eighty, Lecener says that extreme pressure had forced event
lid to bulge outward, a classic sign of impending eruption,
and landslide took it off. To modify that eruption, Lecner theorizes,
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I suppose humans could have triggered the landslide or removed
the overburden lid through say excavation or even donating a
nuclear device. Of course, nowton a volcano should not be
anyone's first plan, and drilling into the magma chamber to
release the pressures out too. Volcanologist Eric Clemetti, writing on
Wired in likened that theory to trying to bleed to
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death with a needle prick. But we couldn't avert an
erupt and by slowly depressurizing the chamber either Lechner wrote,
we have to get past the misconception that a magma
chamber is like a fluid filled balloon or soda bottle
that we can gently insert a straw and suck out
the lava and gas. We're talking about pressures and volumes
of material that are beyond the capacity of man made equipment.
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He says, would have to drill down several kilometers with
massive pipes hundreds of meters in diameter to handle the
volcanic output that would rush from the chamber. The pipes
would have to withstand temperatures above three thousand, six hundred
degrees fahrenheit that's two thousand degrees celsius, and pressures quote
beyond our capabilities to manage and even comprehend. And then
he adds there would still be the gases held in
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solution by the pressure of the chamber that escape violently
when the chamber depressurized. Generally speaking, it seems the main
problem facing human modication of volcanic eruptions is that it's
laughably impossible. Volcanoes are too big and volcanic eruptions are
too powerful. Yet, says Janet Bab, geologist with the U
s GS Hawaiian vulk cano observatory. Humanity is not completely
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without modification options, Bab rope via email. Humans cannot stop
or control an eruption, but we have taken some actions
to control products erupted from a volcano. Diverting lava flows.
For instance, Bab points to Mount Etna and that three
eruption mentioned earlier, which sent lava flowing into populated areas.
With the lava flow threatening to overrun three towns, hundreds
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of workers desperately constructed a system of massive rebel barriers
to redirect it, and it worked. They successfully diverted the lava.
Attempts to guide lava flows by bombing them have generally failed.
Cooling them has shown promise, though. In ninety three, when
lava from a volcano on the Icelandic island of Haymi
was flowing into towns, officials built barriers to stop its
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progress and dumped seawater on the lava to cool it down,
slow the flow, and help it harden. The barriers held
against the lower energy lava flow. As for exerting control
before the lava starts flowing, Lechner says it's mostly science
fiction daydreaming volcanology research instead focuses on advancing methods of
monitoring and prediction. However, he writes, it's not absurd to
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think that our own hubrists might encourage us to attempt
to modify a volcanic eruption. Humans have a history of
large scale engineering feats that have forever modified the service
of the Earth. Today's episode is written by Julia Layton
and produced by Tristan McNeil. For more on this and
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lots of other explosive topics, visit our home planet, how
Stuff Works dot com.