20 terms

Volcanoes

STUDY
PLAY
magma
Molten (melted) rocks found deep in the earth.
lava
This is what magma is called after it leaves the Earth's interior.
The Ring of Fire
This refers to the large number of volcanoes in the Pacific ocean along the convergent plates. The majority of the world's active volcanoes are found here.
hot spots
This is usually caused by plumes of magma in the mantle. Tectonic plates move over these regions and volcanoes form on the plates. The Hawaiian islands were formed this way.
shield volcano
Broad, gently sloped mountain typically formed by hot spots. This is the largest of the volcano types.
cinder cone volcano
Generally these are small, steep mountains formed by the side vents of shield and composite volcanoes.
composite volcano
Typically described as cone shaped these mountains are formed over time from layers of ash, lava, and volcanic rocks.
crater
The bowl shaped impression left after a volcano explodes.
caldera
A large depression in the ground caused when the weight of the volcano collapses because the magma chamber was emptied.
magma chamber
A pocket in which magma collects under a volcano before it erupts.
volcanologist
a person who studies volcanoes
pyroclastic flow
A hot, high-velocity mixture of ash, gas and fragmented rock that flows almost like a liquid down slopes and over terrain.
lahar
A mudflow composed of water and volcanic ash. These are usually triggered by the flash melting of the snow cap of a volcanic mountain or from heavy rain. They are very dangerous because they can occur suddenly and travel at great speeds.
active volcano
Any volcano that has erupted in the last 10,000 years or has the potential to erupt again.
dormant volcano
A volcano that has not erupted for a long period of time and is not expected to erupt anytime soon.
extinct volcano
A volcano which has not erupted for ~10,000 years and is not expected to erupt again.
Signs that a volcano might erupt
Tremors, an increase in size of the volcano, or an increase in heat or gas emission.
tiltmeters
Devices used to measure deformation (size change) in an active volcano.
volcano vent
An opening created when volcanic material is emitted. All volcanoes contain a central one, side ones often form.
cone of a volcano
These are created by the build up of lava solidifying over the course of multiple eruptions.