Mount St. Helens: A Catalyst for Change

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Narrator:
The May 18,  

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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 

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uncorked a lateral blast that 
flattened 230 square miles... 

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in a matter of minutes.

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For nine hours after that, 
a vigorous eruption column 

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billowed into the atmosphere 
coating everything downwind

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with ash. Local rivers were 
inundated by mudflows and debris 

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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 

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U.S. Geological Survey and 
the University of Washington’s

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Pacific Northwest Seismographic 
Network were closely 

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monitoring Mount St. Helens.

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C. Dan Miller:
But it was truly  

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only the beginning of an eruptive episode that 

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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 

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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 

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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 

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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 

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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 

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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  

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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 

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to deploy new and improved monitoring equipment.

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Dan Dzurisin
Today we deployed  

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with a helicopter a multi-sensor instrument 

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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. 

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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 

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did was deploy ground deformation instruments

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out on the outer flanks of 
the volcano and learned that 

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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. 

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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 

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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. 

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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 

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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 

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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? 

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Is the rate increasing or 
decreasing? How does the rate

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correlate with seismic 
activity? When we’re having more 

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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? 

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And therefore producing fewer 
earthquakes. We don’t know

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such fundamental things. And 
understanding those kinds of 

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relationships is key to trying 
to interpret the processes that

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are going on understanding where 
the volcano might be headed 

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and therefore mitigating any hazards 
associated with future activity.

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Narrator:
Volcano  

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science and volcano monitoring have developed 

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impressively since May 18, 
1980. Technology such as GPS,

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infrared imaging, acoustic 
flow sensors and Dopler Radar 

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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 

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eruptions, mud flows, debris 
flows, debris avalanches and

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airborne volcanic ash. The 
realization that volcanic ash can 

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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 

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of erupting. With responsibility 
for monitoring these

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volcanoes the USGS now operates 
volcano observatories focused 

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on Hawaii, Alaska, The Cascades, Yellowstone and

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Long Valley in California. 
One important aspect of this 

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operation is the Volcano Disaster 
Assistance Program (VDAP)...

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a team of scientists with a 
cache of monitoring gear that 

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responds to volcanic unrest across the planet.

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Among the VDAP success stories 
was the forecasting of the 

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1991 Mt. Pinatubo, Philippines 
eruption in time to save

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thousands of lives and to 
evacuate planes and people from 

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US run Clark Air Base.

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Awe inspiring, spectacular 
and scary all characterize the 

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eruption of Mount St. Helens on May 18, 1980.

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The human response to this 
catastrophic event has laid the 

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groundwork for saving lives 
and better addressing future

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volcanic eruptions wherever they might occur.