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welcome back to week two and video four we are going to move
forwarding into
the major volcanic hazards that are associated with volcanic activity
um... Now a great website to visit is this volcanoes.usgs.gov.
um... it has a great inactive map
to look at
which you can see here
um... shows you all over the united states
uh... the different
volcanoes, a little watch eye on Kilauea because it is currently active
and all sorts of awesome features
uh... you can go to different observatories Alaska, Hawaii,
Washington, Oregon
uh... great website to explore
um... and they focus a lot mainly on the cascades
uh... the major eruptions that he had in the past and what's happening now
monitoring these volcanoes
but also the CVO or the Cascade Volcano
Observatory
um... also has as a program where they can monitor and help other countries
that have active volcanoes present as well
which is pretty neat
so uh... some other hazards that are associated with volcanoes
especially with Cascade volcanoes are earthquakes
landslides, pyroclastic flows, lahars
ash or tephra in lava flows
uh... ash or tephra is what is shot up into the air here in this
photograph
uh...and it can travel for miles or around the globe
if the winds are
right
the gases present can produce acid rain
uh... we can get what are called pyroclastic flows which is basically a very hot,
dense
flow that hugs the surface of the earth
and basically incinerates everything in its path and can move
uh... faster than a car. It can go hundreds of miles per hour
Its just absolutely crazy
um... lahars are produced when you have water or ice mixed in with this hot
material
melts the ice and then all the stuff
flows in a big slurry
down slope through any
um... valleys that exist and then lava flows are typical lava flows um
that exist as well
um...so what we can do is after
the major Mount St. Helens eruption uh, what the
uh... USGS did was to produce this hazard map so most volcanoes have
this um
for them you can look at the USGS site and find one for
mount hood or do that here in the lab and
uh basically it uses historical data and geologic data to
basically figure out okay,
when this volcano erupt in the past, what was affected, where did this
debris go
who it needs to be warned
if this volcano is gonna go
um...so we have three different zones on this map, zone one is basically the danger
zone
this is like if you're in this area
you'd better run um or
hide
because basically you're gonna be um vulnerable to
uh... some pretty
hot pyroclastic flows, lava
flows um and maybe
some lahars. Zone two
a little further away in yellow
pyroclastic surges and flows and then zone three
means you follow some of these valleys and those are the areas
that will be inundated by the lahar flows
You can see that some of that debris can go as far as the Columbia River and when Mt. St. Helens
blew in 1980
the Columbia River had to be dredged because there was so much debris
that made it down there
so what um, the USGS has done is built these sediment retention structures
which is basically a dam that will stop these flows, let the particles settle out and then they
drain the water off later
to stop that material from clogging up the rivers flow
here you see
Mt. St. Helens eruption, here's the tephra, the ash that went up into the
air and then the pyroclastic flow that hugged
the surface
um.. and this was produced by
a landslide that basically
collapsed one side of the mountain as it was erupting
pretty intense stuff
we also can get lava flows these are even more of a hazard in Hawaii where we have
these effusive eruptions
that can be produced. They're um
pretty much unstoppable but
if they are small enough you might be able to divert using rock walls or
uh... water if it's small enough
um... that usually not gonna stop it
you can only divert it. An example is um in Hawaii
when the Puʻu ʻŌʻō
volcano erupted
and basically buried and entire community
um they couldn't stop it, it was too much lava, too fast and the whole place was
just gone
which is sad
there is one person actually who still lives there he was protected his
house did not get lost but he as to hike in and out because all the roads
are destroyed
You also can get Tsunami so when a volcano erupts, if enough material falls
into the ocean
or a sub-marine volcano occurs you can get Tsunamis that are produced
um... and
kinda the um
silver lining here is that
these
um... volcanoes have a pretty extensive monitoring system on them so
the Cascades Volcano
Observatory is um..
pretty awesome at
at monitoring all these volcanoes and
being able to figure out what's happening, is there going to be an eruption, should we warn
people
and here on Mt. Rainier we can see in the foreground here, um
a monitoring site that has a that monitors seismic activity earthquakes
the tilt of the surface
and the GPS
uh... so basically what they do at these sites is they
um... measure some small
earthquakes that can be produced as magma is moving underneath the surface
that can be a sign
that the volcano is going to blow
measuring the surface
tilt
can be another
another warning sign if magma
and pressures building up inside the earth the surface is going to be deformed
and then GPS units to see if things change at all
it's a great map
that you can view
um...
of Mt. Rainier and has all these different
monitoring sights, you can click on each one it tells you
what it's monitoring and it can you can look at this is monitoring seismic and if we look at the seismic data
for the last twenty four hours we can
see how many earthquakes have happened which is pretty neat
I'll let you guys explore that on your own time
those are the major hazards so make sure you visit those websites we're gonna
look at them in lab as well
and make sure you're prepared because we live in a
hazard zone, we live close to a volcano and you
need to know
what to do you if it goes. so check out those websites