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Shield Volcano – Mafic Lava See how dark the rocks are & how flat the volcano is!. Basic Facts for Shield Volcanoes. Viscosity – low Gas Solubility – low Minerals – Ca feldspar, Olivine & Pyroxene Rocks – Basalt Magma type – Mafic Boundary – Divergent. Lava Tubes.

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basic facts for shield volcanoes
Basic Facts for Shield Volcanoes
  • Viscosity – low
  • Gas Solubility – low
  • Minerals – Ca feldspar, Olivine & Pyroxene
  • Rocks – Basalt
  • Magma type – Mafic
  • Boundary – Divergent
slide5

Aa – Blocky, sharp, rocks (They got their name because they hurt when you walk on them barefoot.)

flood basalts happen when a shield volcano pours out very large amounts of lava
Flood Basalts happen when a Shield volcano pours out very large amounts of lava.

Located in Washington, Oregon & Idaho this flood covers 63,000 square miles.

Up to 3000’ thick

fissure eruptions curtains and fountains these are all calm volcanic features
Fissure Eruptions, Curtains, and fountains – These are all “calm” volcanic features!

Fissure

Fountain

Curtain

Of fire

hawaiian eruptions
Hawaiian Eruptions
  • Calm
  • Fluid Lava Flows
  • Out-pouring of basaltic lava
slide11

Iceland – Laki 1783; huge flood basalt from a fissure eruption, caused an “Iceland Haze” of poison gas of fluorine which killed all the crops & livestock which caused 9000 people (1/4) of Iceland population to die.

fumarole aka poison gas
Fumarole: aka: Poison gas

1986 Cameroon Africa – Lake Nyos

Gas killed all living things in a 15 mile radius including 1,700 people.

cinder cones hot the same as shield volcanoes except they are rock pieces not lava flows
Cinder ConesHot – the same as Shield Volcanoes except they are rock pieces & not lava flows!

Paricutin

Puu Oo – Hawaii

Parasitic –

strombolian
Strombolian
  • short-lived,
  • explosive outbursts of pasty lava
  • Do not make pele’s tears or hair
  • dominated by scoria/tephra fragments
  • little or no flowing lava
basic facts composite
Basic Facts - Composite
  • Viscosity - high
  • Gas Solubility - high
  • Minerals – quartz, m.mica & K-feldspar
  • Rocks - granite
  • Boundary – convergent (continent to ocean or ocean to ocean)
  • Magma - felsic
plinian eruption huge plumes of ash thrown into the stratosphere
Plinian Eruption – Huge plumes of ash thrown into the Stratosphere.
  • Vesuvius – 79 AD
  • 2000 people died – covered in ash
  • Mt. St. Helen’s – 1980
  • 57 lives lost
nuee ardente
Nuee Ardente

nuées ardentes – “glowing clouds”, “ glowing hurricane” – blistering torrents of steam, ash, pumice, and red-hot rock that were coughed from craters and charged down volcanic slopes, obliterating everything in their path. 400 degree dust & ash moving over 100 mph

lahars aka flood
Laharsaka: flood

Mud Flow

Debris Flow

lahar at mt st helens
Lahar at Mt. St. Helens
  • The lahar carries away a bridge spanning the Toutle River about 20 miles downstream from Mount St. Helens volcano on May 18, 1980.
deadly lahars from nevado del ruiz colombia november 13 1985
Deadly Lahars from Nevado del Ruiz, ColombiaNovember 13, 1985
  • Río Lagunillas, Within four hours of the beginning of the eruption, lahars had traveled 60 miles and left behind a wake of destruction: more than 23,000 people killed, and most of the town destroyed.

ember 13, 1985

fumarole aka poison gas1
Fumarole: aka: Poison gas

Happen at Convergent boundary Volcanoes also.

rhyolite caldera complex
Rhyolite Caldera Complex

Magma - felsic

Rocks - granite

Viscosity – very high

Gas Solubility – very high

Minerals – quartz, m.mica, k-feldspar

krakatoa
Krakatoa

36,000 lost their lives in 1883 most deaths caused by tsunamis which hit 295 towns

Could be heard from 1000 miles away.

Recordable sound waves circles the earth 7 times lasting 5 days.

Ash fell 300 miles away in Singapore.

Rafts of floating pumice thick enough to support people crossed the Indian Ocean in 10 months and were still afloat two years after the eruption.

tambora
Tambora
  • The caldera is over 3,000’ deep
  • And 5 miles in diameter

Killed 100,000 people 15,000 directly & the rest due to starvation

tambora a year without summer

Rain, Rain Go Away - Ireland experienced persistent cold rain for 142 of the 153 summer days. The cold weather destroyed their wheat, oat and potato crops.

  • Hungary, January 1816 - Brown Snow?In January 1816, a blizzard of brown snow hit Hungary.
  • Britain, Autumn 1815 - In response to the food shortage caused by the “Year without Summer”, the British government abolished income taxes in 1816.
Tambora A Year Without Summer
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