USGS Multimedia Gallery: (Video)--Mount St. Helens: A Catalyst for Change

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Narrator:
The May 18, 1980 eruption of Mount St. Helens was
a seminal moment for volcanology

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On that fateful morning, an earthquake and giant landslide
uncorked a lateral blast that flattened 230 square miles...
in a matter of minutes.

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For nine hours after that, a vigorous eruption column
billowed into the atmosphere coating everything downwind

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with ash. Local rivers were inundated by mudflows and debris
flows that took out bridges and homes for miles downstream.

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For two months prior to May 18, 1980 scientists with the
U.S. Geological Survey and the University of Washington’s

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Pacific Northwest Seismographic Network were closely
monitoring Mount St. Helens.

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C. Dan Miller:
But it was truly only the beginning of an eruptive episode that
lasted for over 6 years. So the first explosion occurred

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on May 18 and then there were several sizeable explosions in
the summer of 1980 and they sort of trailed off until

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October of 1980 and then for the next five years or five and
a half years there were a series of dome building eruptions

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in which molten material came out, very viscous pasty lava
come out on the floor of the crater and piled up to form a

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dome or a mound in the middle of the crater floor a feature
that’s now about 900 feet high sitting on the floor of the crater.

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So, this episode at Mount St. Helens which began on May 18
actually culminated in October of 1986 when the last magma

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came out of the ground.

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Narrator
The volcano reawakened again in 2004 displaying another period
of dome building and smaller explosive eruptions.

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This resumed unrest was an opportunity for the scientists
to deploy new and improved monitoring equipment.

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Dan Dzurisin
Today we deployed with a helicopter a multi-sensor instrument
package that was developed literally in the past week or at least

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fabricated in the past week at the Cascades Volcano Observatory.
This was in response to what we’ve been learning at the volcano

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over the past two and a half to three weeks. The first thing we
did was deploy ground deformation instruments

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out on the outer flanks of the volcano and learned that
they weren’t moving. Then last week we deployed three GPS

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instruments on the old part of the lava dome itself.
And discovered that it’s moving very little if at all at the

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same time that the feature on the south crater floor is moving
by tens of meters and so we wanted to get instruments directly

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on the part of the dome that’s moving so dramatically.
And so we very quickly put together a GPS sensor, a seismometer,

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a tilt meter and a microphone, the microphone will record the
sound of explosions should they occur and that’s important if they

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occur in the middle of night or in bad weather we’ll have some indication
that that’s what's happened and integrate that into our data stream.

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We’d like to know for example is the deformation continuing?
Is the rate increasing or decreasing? How does the rate

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correlate with seismic activity? When we’re having more
earthquakes is the ground deforming more rapidly or less

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rapidly because it’s easier for magma to move up the pipe?
And therefore producing fewer earthquakes. We don’t know

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such fundamental things. And understanding those kinds of
relationships is key to trying to interpret the processes that

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are going on understanding where the volcano might be headed
and therefore mitigating any hazards associated with future activity.

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Narrator:
Volcano science and volcano monitoring have developed
impressively since May 18, 1980. Technology such as GPS,

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infrared imaging, acoustic flow sensors and Dopler Radar
are just a few of the new tools available to the scientists.

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They are studying hazards from lava flows to explosive
eruptions, mud flows, debris flows, debris avalanches and

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airborne volcanic ash. The realization that volcanic ash can
stall a jet engine adds urgency to monitoring explosive

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eruptions and any ash clouds that may threaten aircraft.

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In the US and its territories there are 169 volcanoes capable
of erupting. With responsibility for monitoring these

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volcanoes the USGS now operates volcano observatories focused
on Hawaii, Alaska, The Cascades, Yellowstone and

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Long Valley in California. One important aspect of this
operation is the Volcano Disaster Assistance Program (VDAP)...

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a team of scientists with a cache of monitoring gear that
responds to volcanic unrest across the planet.

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Among the VDAP success stories was the forecasting of the
1991 Mt. Pinatubo, Philippines eruption in time to save

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thousands of lives and to evacuate planes and people from
US run Clark Air Base.

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Awe inspiring, spectacular and scary all characterize the
eruption of Mount St. Helens on May 18, 1980.

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The human response to this catastrophic event has laid the
groundwork for saving lives and better addressing future

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volcanic eruptions wherever they might occur.