Transcript Volcano WebQuest Follow-Up

Volcano WebQuest Follow-Up
A volcano is:
• An opening in the earth’s crust that allows
magma, pyroclasts, and gases to escape
Volcano Features:
• Dome: build up of lava and debris surrounding
a vent to form a volcano
• Vent: the opening in the earth that volcanic
materials get erupted from
Things that can come out of a volcano:
• Lava: molten rock, ability to flow depends on
Silica and moisture content (called magma when
found inside the earth), made up of crystals
volcanic glass, and bubbles
• Ash: rock, mineral, volcanic glass (all pieces
ejected are around the size of a pinhead)
• Tephra: fragments exploded from a volcano
(bomb, block, lapilli, ash, cinder)
• Lahar: fast moving mix of rock pieces and water,
like a fast moving river of muddy rock
• Gas: CO2, H2Ovapor, SO2
• Pyroclastic Flow: avalanche of hot volcanic
materials, travel very quickly
People tend to live near volcanoes
because:
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They have very fertile soils
Contain valuable mineral deposits
Are very scenic
Tourism
Bad things volcanoes can do to the
environment:
• Destroy the land
• Kill plants, animals, and people
• Put deadly gases
into the air (short term)
• Provide about 3%
of yearly CO2 output
Viscosity is:
• The ability of a material to resist flow.
How does viscosity effect an eruption?
• The more viscous the lava, the more explosive
the eruption.
• More viscous materials flow very slowly so
they ‘jam up’ the volcano vent until there’s
too much pressure and they explode.
Stratovolcano
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Lava viscosity=High
Gases: high which leads to explosive eruptions
Size: medium
Eruption Style: alternates eruptions of lava
flows and pyroclastic flows/explosions
• Found: subduction zones
• Examples: Mt Fuji, Mt St Helens,
Krakatoa
Cinder Cone
• Lava viscosity=Highest
• Gases: high, gas charged lava carries lava up in
lava fountains
• Size: smaller with narrow piles of pyroclastic
particles
• Eruption Style: explodes vertically with small
cinders forming and falling straight back down
• Found: typically found on sides of other
volcanoes
• Examples: Paricutin, Wizard Island
Shield Volcano
• Lava viscosity=Low
• Gases: low
• Size: largest , big base with gently sloping
sides
• Eruption Style: fluid flow from all directions
around vent
• Found: Hotspots
• Examples: Hawaii,
Galapagos, Iceland
Hotspots are:
• Areas of volcanism not at plate boundaries.
• Magma finds a weak spot in the earth’s crust
and forces it’s way up to the surface.
• Ex: Hawaii, Yellowstone
How was Hawaii formed?
• The Pacific Plate is moving Northwest over the
stationary hotspot that supplies magma to the
Hawaiian volcanoes.
• As a result, an island chain formed with the
oldest volcano being the
furthest NW and the
youngest (and still active
one) being the furthest
south.