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PCS Earth Science
Chapter 19 Vocabulary - Earthquakes
Term | Definition |
---|---|
epicenter | point on the Earth's surface directly above the focus of an earthquake |
fault | fracture or system of fractures in Earth's crust that occurs when stress is applied too quickly or stress is too great |
focus | point of the initial fault rupture when an earthquake originates that usually lies at least several kilometers beneath Earth's surface |
magnitude | measure of energy released during an earthquake, which can be described as the Richter Scale |
modified Mercalli scale | measures earthquake intensity |
moment magnitude scale | a scale that rates earthquakes by estimating the total energy released by an earthquake |
primary wave | seismic wave that squeezes and pulls rocks in the same direction that the wave travels, causing rock particles to move back and forth |
Richter scale | scale used to measure magnitude |
secondary wave | seismic wave that causes rock particles to move at right angles to the direction of the wave |
seismic gap | place along an active fault that has not experienced and earthquake in a long time |
seismogram | record produced by a seismometer that can provide individual tracking of each type of seismic wave |
seimometer | instrument used to measure horizontal or vertical motion during an earthquake |
strain | deformation of materials in response to stress |
stress | forces per unit area that act on a material compression, tension, and shear |
surface wave | seismic wave that moves in two directions as it passes through rocks, causing the ground to move both up and down and side to side |
Tsunami |