Transcript 4. Where Volcanoes are Found PPT

Where are Volcanoes Found?
3b - Students know the principal structures that form at the three
different kinds of plate boundaries.
3c - Students know the explanation for the location and properties
of volcanoes that are due to hot spots and the explanation for
those that are due to subduction.
1. Divergent Plate
Boundaries (15%)
2. Convergent Plate
Boundaries (80%)
3. Hot Spots (5%)
1. Divergent Boundaries
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Rift volcanism (ocean ridges)
Mostly under the oceans
Basaltic magma – Shield Volcanoes
On land – Africa & Iceland
• Subduction Zones (convergence of oceanic plates)
• Andesitic magma or Rhyolitic magma – Composite
Volcanoes
a. Circum-Pacific Belt -Pacific Ring of Fire
b. Mediterranean Belt
Mediterranean
Belt
Ring of
Fire
• Unusually hot areas of Earth’s mantle
• Hot plumes rise toward the crust…forming
magma and volcanoes
• As the lithosphere moves over a hot spot….a trail
of progressively older volcanoes forms
• Hawaii &
Yellowstone
• If hot spot is under the ocean = non-explosive
basaltic magma
• If hot spot is under the continents = explosive
rhyolitic magma