A volcano is an opening in the Earth’s crust where lava comes out.

A volcano is an opening in the Earth’s crust where lava comes out

Volcanoes can be found in 3 general locations

1. Divergent Boundaries2. Subduction boundaries3. Hot Spots

At divergent boundaries, volcanoes are created as the plates slide apart. Iceland is a good example.

When one plate subducts under another, a volcano is created. A good example is Mt. Fuji in Japan, Mt. St Helens in Washington and Aleutian islands in Alaska

Hot Spots are volcanoes that form in the middle of a tectonic plate. Hawaii is an example. As the plate moves, the hot spot stays in the same place, so a chain of islands is often created.

There are 3 kinds of volcanoes1. Shield Cone2. Cinder Cone3. Composite Cone

Shield Cone volcanoes are not very tall and formed by layers of lava.

Quiet Eruptions

Steep Volcano with explosive eruptions.

Explosive eruptions caused by gas.

Formed by layers of volcanic rock

Made of alternating layers of lava and rock

Alternates in explosive eruption and quiet eruptions

AKA Stratocones

Mafic lava – dark, no gas, not explosive, thin

Felsic lava – light, lots of gas, explosive, thick

Pahoehoe – ropey cooled lava, usually from mafic lava

Aa – thick, blocky cooled lava from felsic lava

pahoehoe

aa

Vent – name of actual opening of volcano

Crater – surrounding area around vent. Caldera – a collapsed vent; after a

volcano explodes, a huge opening left over from explosion.