Active VolcanoA volcano that show signs of eruption or has erupted recently.
AshSmall pieces of magma thrown out of a volcano. The ash pieces that fall near the
volcano opening form the crater.
CalderaA large circular hole, usually over a mile in diameter, produced when a volcano
collapses upon itself.
Cone VolcanoA steep, sloping volcano made of layers of ash and lava that builds up from past
eruptions.
ConvectionA circular movement in a liquid that carries heat from one place to another. In the
earth it occurs in the mantle.
CraterThe large opening at the top of a volcano produced by the explosion of an eruption.
It is smaller than a caldera.
CrustThe layer of hard rock that surrounds the earth. It is between 21 and 125 miles
thick.
Dormant VolcanoA volcano that has not erupted for a long time, but may erupt again one day.
EruptionThe sudden explosion of hot rocks, gases, and other material through a hole in the
earth's surface.
Extinct VolcanoA volcano that has not erupted for thousands of years and probably will not erupt
again.
Geothermal EnergyEnergy made using underground steam; the steam is used to produce electricity.
LaharA volcanic mudflow which is a mix of water, volcanic ash, and some gases which
moves very fast down a valley.
LavaThe hot liquid magma that flows from a volcano during an eruption. It is magma
that has lost all its gases but is still liquid. There are two main types of lava: thick,
sticky lava and liquid, runny lava. It is usually orange, red, or yellow and is over
1,470 degrees Fehrenheit.
Lava FlowLiquid magma that flows over the earth's surface.
MagmaThe melted rock produced inside the earth. When a volcano erupts magma comes
to the surface and is called lava.
Mantle-
The layer of hard rock immediately between the earth's crust and core. Beneath the
mantle, some of the rocks are liquid and move.
MudflowA flow of water and debris that usually looks like brown liquid cement. Heavy rain,
melting snow, and ash mix together during an eruption and produce mudflows.
PlateA section of the earth's crust made by weak spots in the crust and boiling magma. It
floats on the mantle layer. Often volcanoes and earthquakes occur at the edges of
the earth's plate.
Volcanic AshLava from a volcano that is in the form of chunks smaller than an apple, about the
size of a marble.
Volcanic BombA large lump of lava thrown out of a volcano during an eruption. A bomb usually
starts as a flying blob of lava but solidifies as it falls to the ground.
Volcanic DustLava in the form of small particles thrown from a volcano during an eruption.
Volcanic MaterialLava, ash, and gases that are brought to the surface when a volcano erupts.