Volcanoes

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Volcanoes

• Chapter 10 Earth Science Book

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• The 3 factors that affects whether or not an
  eruption is violent are
• Magma composition
• Magma temperature
• Dissolved gasses in the magma

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Kinds of Magma

• Basaltic low silica (-50), least dissolved
  gasses, least amount of pyroclastic material,
  least viscosity least explosive.

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• Andesitic medium silica(-60), intermediate gas
  content, intermediate amount of ejected rock
  material, medium viscosity

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• Rhylotic highest silica, highest gas content,
  most pyroclastic material, highest viscosity.
  Most explosive.

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• Pyroclastic material is the name given to
  particles produced in volcanic eruptions.
• The smallest particles are called lapilli
• The largest are called lava bombs

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Shield Volcano

• Built by build up of fluid basaltic lava flows.
• Very broad (wide) sloping sides (not steep)

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Cinder cones

• Formed by ejected fragments called cinders
  (basaltic scoria)

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• Simple cone shape, steep sides

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• Smallest of the volcanoes short life span.

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Composite Volcanoes

• Most dangerous volcanoes (located mostly around
  the ring of fire)

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• Symmetrical structure composed of both lava and
  pyroclastic deposits.

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• High gas silica content, explosive lava eject
  large amounts of pyroclastic ejecta.

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Ten Most Deadly Eruptions!

• Mt. Vesuvius (Italy) December 1651
• 4000 people killed

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Number 9 - Kelut Volcano, Java May 19, 1919

• 5000 people killed

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8 Laki, Iceland (June 8, 1783)

• 9380 people killed from lava flow, disease and
  starvation

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Mt. Kelut again

• 10,000 people killed in 1581

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6 Unzen, Japan on 5-21-1792

• 14,500 killed

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5 Mt Vesuvious again

• August 24, 79 AD The famous eruption that
  destroyed the city of Pompeii 16,000 people
  were killed!

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4 Ruiz Nevado, Columbia

• November 13, 1985 23,000 killed due to a giant
  lahar (mudflow)

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3 Mt. Pelee, Martinique

• May 8, 1902 28,000 killed due to pyroclastic
  flow!

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2 Krakatoa, Indonesia

• Aug. 26-28, 1883 36,000 people killed. The
  blast could be heard 2,200 km away in Australia!
  People were killed from ash fall and a Tsunami.

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1 Tambora, Indonesia

• April 10-12, 1815 92,000 people were killed
  due to ash fall, tsumani, disease and starvation.