Chapter 15: Earthquakes and Volcanoes 8th grade

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Terms in this set (...)

Earthquakes
Sudden violent movements of earths crust
Fault
A break in a body of rock along which one block slides relative to another
Seismic Wave
Vibrations that travel through Earth carrying the energy released during an earthquake.
Focus
The point beneath Earth's surface where rock breaks under stress and causes an earthquake
Epicenter
Point on Earth's surface directly above an earthquake's focus
primary wave
cause particles in the ground to move in a push-pull motion similar to a coiled spring
secondary wave
cause particles to move up and down at right angles relative to the direction the wave travels
seismologist
A scientist who studies earthquakes
seismometer
Instrument used to measure horizontal or vertical motion during an earthquake.
seismogram
A tracing of earthquake motion that is created by a seismograph
surface waves
cause particles in the ground to move up and down in a rolling motion
Volcano
A weak spot in the crust where magma has come to the surface
Magma
Molten rock beneath the earth's surface
Lava
Magma that reaches Earth's surface
hot spot
volcanoes not associated with plate boundaries
shield volcano
a wide, gently sloping mountain made of layers of lava and formed by quiet eruptions
composite volcano
large, steep-sided volcanoes that result from explosive eruptions of andesitic and rhyolitic lava and ash along convergent plate boundaries
cinder cone
small, steep-sided volcanoes that erupt gas-rich, basaltic lavas
volcanic ash
tiny particles of pulverized rock and glass
viscosity
a liquid's resistance to flow
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