volcano webquest follow-up. a volcano is: an opening in the earth’s crust that allows magma,...
TRANSCRIPT
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:
• 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
• 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 activeone) being the furthest
south.