24 terms

Earthquake & Volcano Checkpoint

STUDY
PLAY
Stress
a force that acts on a rock to change its shape or volume
Tension
a stress that pushes a mass of rock in two opposite directions
Anticline
a fold in a rock that bends upward into an arch
Focus
the point beneath Earth's surface where rock breaks under stress and triggers and earthquake
P-waves
the type of seismic waves that arrive at the surface first and move by compressing and expanding the ground like an accordion
Moment magnitude scale
the scale that measures the total energy released by an earthquake
Mercalli scale
the scale used to tell how much eartquake damage was done to homes and other buildings
Magma
molten rock material before it reaches the surface
Igneous rock
when molten material cools, hardens and crystalizes
Silica
the main factor that accounts for the difference between quiet and explosive volcanic eruptions
Composite volcanoes
tall, cone-shaped mountains in which layers of lava alternate with layers of ash
Lava plateau
many layers of thin, runny lava that build up a high, level area
Caldera
the huge hole left by the collapse of a volcanic mountain
Cinder cone volcano
ash, cinders, and bombs build up in a steep pile around a volcano's vent
Shield volcano
a wide, gently sloping mountain produced by layers of lava flows
Magma chamber
a place deep within the volcano that contains molten material
Pipe
a long tube that extends from Earth's crust up through the top of the volcano
Central vent
where gas and molten rock leave at the top of the volcano
Lava flow
the spread of lava as it pours out of a vent
Compression
a stress that pushes two masses of rock together
Shearing
a stress that slides two masses of rock past each other
S-waves
the type of seismic waves that arrive at the surface second and move the ground side to side
Surface waves
the type of seismic waves that are the slowest moving and cause the most damage
Epicenter
the point on the surface directly above where the earthquake begins