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15 terms

volcanoes & earthquakes

vocabulary
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VEI
provide a relative measure of the explosiveness of volcanic eruptions.
Composite Volcano
made of alternating layers of hardened lava flows and pyroclastic material. Layers alternate between quiet lava flows and explosive eruptions to commonly develop large volcanic mountains.
Shield Volcano
cones are broad at the base and have gently sloping sides. Forms from quiet eruptions.
Cinder Cone Volcano
A type of volcano that has very steep slopes and form from explosive eruptions and are made of pyroclastic material.
Seismic Waves
Energy in the form of vibrations that is released from rocks that have slipped into new positions along a fault.
Primary (P) Waves
the fastest seismic waves and are always the first waves of an earthquake to be detected. Can move through solids, liquids, and gases in a back-and-forth direction.
Secondary (S) Waves
the second fastest seismic waves. Cause particles of rock to move in a side-to-side direction perpendicular to the waves traveling. Can travel through only solid material.
Surface (L) Waves
The slowest-moving waves that may cause the most damage during an earthquake. Known as Love waves and Rayleigh waves.
Richter Scale
measures the ground motion from an earthquake to find the earthquake's strength.
seismograph
an instrument that records vibrations in the ground.
seismogram
a tracing of earthquake motion that is recorded by a seismograph.
Mercalli Scale
expresses intensity of earthquake and provides a description of the effects of each earthquake intensity.
Moment Magnitude Scale
a measurement of earthquake strength based on the size of the area of the fault that moves, the average distance that the fault blocks move, and the rigidity of the rocks in the fault zone.
Hot Spot
a volcanically active area of Earth's surface, commonly far from a tectonic plate boundary.
Caldera
a large, circular depression that forms when the magma chanber below a volcano partially empties and causes the ground above to sink.