Volcano Flashcards
A Volcano is an
opening (crack) in the crust where lava reaches the surface
Volcanoes are generally found where
tectonic plates are diverging or converging
Most divergent plate boundaries are at the bottom of the oceans, causing
most of the volcanic activity to be under water, thus forming new seafloor.
Convergent plate boundaries: When two plates (usually an oceanic and continental plate) collide,
causing the one plate to submerge under the other plate (called subduction).
In the case of oceanic-continental, a deep trench just off shore is formed.
When the thick magma, reaches the surface, a volcano is formed.
In the theory of plate tectonics most of the geological characteristics are explained by
tension (interaction) among plates.
However, some of most spectacular formations are caused by “hot spots” which are situated far from the edges of tectonic plates.
A hotspot is a
place in the middle of a tectonic plate where hot magma rises (called a mantle plume) until it reaches the crust. Magma then flows out.
The Pacific Ring of Fire is
an area of frequent earthquakes and volcanic eruptions circling the basin of the Pacific Ocean.
Result of plate tectonics and the movement and hitting of crustal plates.
Ring of Fire
Area where large numbers of earthquakes and volcanic eruptions occur in a 40,000km horseshoe shape.
Contains 452 volcanoes, with over 75% of worlds active and dormant volcanoes.
There are 3 types of Volcanoes
Shield Volcano
Cinder Cone Volcano
Composite Volcano
Shield Volcano
A gently-sloped volcano (large volcano but not very tall)
built out of layers of lava from lots of little eruptions
Ex. Kohala
Cinder Cone
Most common
Steep sides
Made of cinders (melted volcanic rock that has cooled down)
Ex. Diamond Head
Composite Volcano
A tall volcano made of many layers of cinders and hardened lava
Ex. Mount Shasta
