Volcano CS

Página 1

Mt. St. Helens

Erupted 1980

57 dead

USGS monitoring

Bulge on the northern face

Destroyed 230 miles sq. of forest

May 18th- largest landslide in recorded history

9 hour eruption

huge ash cloud

____ river valley filled 150ft in mud and ash for 14 miles

Columbia river shut down to shipping traffic from ash and mud flows

Eruptions 1980-1986, 2004-2008. 1980-1986 able to accurately predict so could to research on hot ash deposits

forest area surrounding filled with cabins, lakes, youth camps

tuutle river- beautiful area, totally destroyed

sumer cabins, lodges, youth camps. skiing on the mountain, ice hiking

trout fishing

loss or recreation

mountain built last 2500 years

grown up since last glaciation

smooth, symmetrical, cone shaped

much like mt. Fuji in Japan

timber industry

dougles fir- best building wood in world

eruption 1857

warning deep long earthquakes right under mtn

lsrge cracks forming

buildup

one seismometer

scramble to establish seismometers

people dont feel in danger

would think would be too large a time frame between eruptions

silver lake evidence of past eruptions

cave basalt lava flows from when used to be basalt

can find ash from mt st helens in canada

large verticlal ash cloud

melting snow, pressurised steam, drying out inside

more primitive instrumentation

laser range finder

targets- prisms

5 ft a day, thought 5 ft per day is incorrect

mtn being split into two

stubborn people stayed in red zone

outside red zone warned to be prepared

vancouver vancouver this is it ! then died, johnston ridge

bulge collapsed, landslide. crashed into spirit lake, wave- lake up

current bottom of lake above former surface.

supersonic speed

350 m/hour

500 atomic bombs

first 600 miles, no trees or dirt- blown to bare rock

johnston ridge, pulled trees apart, tearing them - dave johnston

then began to slow, following topography, ground hugging, patterns of jackstraw trees, recorded direction of blast. two miles past that heat kill zone, no longer travelling fast enough but hot enough to kill in standing position. standing dead forest. then vent was open, direct pipe to magma chamber so mountain began erupting vertically. prevailing wind direction NE.

day--> night in NE Washington

Many kepy out of harms way - would have inundated several cities- 300 people- if they hadn't evacuated

fortunate it happened on a sunday

president carter

trees turned into toothpicks

highway missing

pyroclastic flows- vaporised any biological remnants

650 miles of road destroyed

new highway constructed to withstand earthquakes, further eruptions; also above valley floor so wouldnt be covered again

army corps of engineers sediment retention dam

made from earth

glacier formed in crater

https://www.youtube.com/watch?v=Ifohb8_2WhE

Página 2

Iceland

https://www.youtube.com/watch?v=MlH7pCK4H-s&spfreload=10

Reykjavik- 2010

10 million flights

heathrow 1000 planes/day

first time ever halt all flights

volcanic glass- destry aircraft engine

scale unheard of in living memory

could be repeated

nobody died

Laki fissure- 20 km fissure

biggest single lava flow on planet

took 4 days for lava to move 34 km?

ongoing for 8 months

1783

fed two enormous lava lakes

expanded across plain and began to close off small farming community

Lava fountains bursting from short fissure- up to 50 m high

Lava fountains 500 m high

Pastor here, Johann Staingrimsun

description from geological and human side

described scene as lava poured out, made its way towards village

lava flow advanced towards homes

fire mass- famous sermon. face situation without fear

Lava stopped 2 km from church. urged people to carry on living life

Lava only part f problem. Eruption produced huge amounts of sulphur dioxide, flourine. Famine swept across Iceland

25% died starvation. Island totally covered with ash

also a mist, no sunlight for months

important chapter in icelanding and in world history

10,000 died

huge cloud sulphur dioxide across continent

starvation across europe

intense smell of sulphur

bloodred sun rising and setting

doubling death rate

worse in France

Heimaey

40 years ago

raining hot gravel

1000C

pure luck fishing boats

most profitable fishing port in iceland

only a single chimney still pokes out of the

Harbour entrance only a few hundred metres wide

now 200 m

eyjafjajokull

international incident

long lasting high pressure over atlantic ocean- winds blew ash over europe

Nobody expected it to be active

5cm thick- black ash everywhere, thicker getting closer

evacuated local farmers

masks to keep ash out of lungs

lambing season in April

adverse health effects on the animals, people- ash in lungs

Life returns to normal in 2 years or so

people live with volcanic eruptions, used to them. Peak in activity every 140yrs

Grimsvotn May 2011 explosive eruption

Geothermal activity Katla- melting of glacier, taking out road. flooding. glacier. Much larger than grimsovtn. Only 20km away from Eyjafjajokull. Closely monitoring Katla.

Katla - Caldera- super eruption 50x bigger deposited ash layers in Russia (2,000 miles away)

1918 Katla huge ash eruption, torrent of meltwater.

GPS instruments use satellite technology to show how mountain moving.

Volcanos change patterns so much, irregular that cannot be predicted; must be carefully monitored.

Magma accumulating kilometers beneath