Earth Science 11 Earthquakes, Volcanoes

Term Definition
S Wave a wave that can move through only solid material
Elastic Rebound the sudden return of rocks to their undeformed shape
Body Wave a wave that moves through a medium
P Wave a wave that moves material back and forth
Surface Wave slowest type of seismic wave
Seismograph records ground vibrations
Richter a scale used to determine the magnitude of an earthquake by using the amplitude and the distance
Mercalli a scale used to measure the intensity of an earthquake
Fault Zone an area where numerous earthquakes occur
Tsunami a giant wave produced by an underwater earthquake
Primary waves are compressional
Surface waves cause the most damage
Lava magma that flows onto earth's surface
Crater hollowed out area at the top of a volcano
hot spot a volcanically active area of earth's surface, commonly far from a tectonic plate boundary
Magma liquid rock that forms under Earth's surface
Pipe vertical crack which magma moves
sill small plutons that intrude the surrounding rock horizontally
vent opening of a volcano which lava flows
mafic magma or rock that is rich in magnesium and iron, dark in color
caldera basin shaped depression that forms after the magma has erupted
dike small plutons that intrude the surrounding rock vertically
felsic magma or rock that is rich in silicate materials
Active Volcano has erupted in the past century and is expected to erupt again
Dormant Volcano is expected to erupt again; hasn't erupted in past
Extinct Volcano hasn't erupted in 10,000 years and won't erupt again
Viscosity the resistance to flow
Pyroclastic Material fragments of rock that form during a volcanic eruption
Focus the location where the earthquake begins
epicenter the point on the earth's surface vertically above the focus of an earthquake
Shadow Zone is the area of the earth from angular distances of 104 to 140 degrees from a given earthquake that does not receive any direct p waves
Fault Zone large faults within the Earth's crust result from the action of plate tectonics forces, with the largest forming the boundaries between the plates
Seismograph an instrument scientists use to measure the strength of an earthquake
Seismogram a record of the ground motion at a measuring station as a function of time
magnitude the relative size of the earthquake
Intensity the severity of the earthquake
Seismic Gap part of the active fault that has experienced little or no seismic activity for a long period, indicating the buildup of stresses that are useful in predicting earthquakes