Earthquakes
Vibrations caused by the rupture and sudden movement of rocks along a break or a crack in Earth's crust.
EARTHQUAKE
The location on Earth's surface directly above an earthquake's focus.
EPICENTER
A vent in Earth's crust through which molten rock flows.
VOLCANO
A location where volcanoes form far from plate boundaries.
HOT SPOT
A crack or a fracture in Earth's lithosphere along which movement occurs.
FAULT
Energy that travels as vibrations on and in Earth.
SEISMIC WAVE
Scientist that studies earthquakes.
SEISMOLOGIST
A large volcano with gentle slopes of basaltic lavas, common along divergent plate boundaries and oceanic hot spots.
SHIELD VOLCANO
Molten rock stored beneath Earth's surface.
MAGMA
Two blocks of rock slide horizontally past each other in opposite directions.
STRIKE-SLOPE FAULT
(transform plate boundaries)
A type of seismic wave that causes particles in the ground to move up and down in a rolling motion.
SURFACE WAVE
An instrument that measures and records ground motion and can be used to determine the distance seismic waves travel.
SEIZMOMETER
A small, steep-sided volcano that erupts gas-rich, basaltic lava.
CINDER CONE
Magma that erupts onto Earth's surface.
LAVA
Forces push two blocks of rock together. The block of rock above the fault moves up relative to the block of rock below the fault.
REVERSE FAULT
(convergent plate boundaries)
A type of seismic wave which causes particles in the ground to move in a push-pull motion similar to a coiled spring.
PRIMARY WAVE (P-wave)
A graphical illustration of seismic waves.
SEISMOGRAM
A large, steep-sided volcano that results from explosive eruptions of andesitic and rhyolitic lavas along convergent plate boundaries.
COMPOSITE VOLCANO
Tiny particles of pulverized volcanic rock and glass.
VOLCANIC ASH
Forces pull two blocks of rock apart. The block of rock above the fault moves down relative to the block of rock below the fault.
NORMAL FAULT
(divergent plate boundaries)
A type of seismic wave that causes particles to move at right angles relative to the direction the wave travels.
SECONDARY WAVE (S-wave)
A location inside Earth where seismic waves originate and rocks first move along a fault.
FOCUS
Large volcanic depression formed when a volcano's summit collapses or is blown away by explosive activity.
CALDERA
A measurement of a liquid's resistance to flow.
VISCOSITY
Where do earthquakes occur?
In the oceans, along edges of continents, and along the plate boundaries.