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Chapter 19
Term | Definition |
---|---|
Stress | Total force acting on crustal rocks per unit area. |
Strain | Deformation of materials in response to stress. |
Elastic deformation | Is caused when a material is compressed, bent, or stretched. |
Plastic deformation | When stress builds up past a certain point, called the elastic limit, rock undergo. |
Fault | Is any fracture of system of fractures along which Earth moves. |
Seismic waves | Vibrations of the ground produced during an earthquake. |
Primary waves | Squeeze and push rocks in the direction along which the waves are traveling. |
Secondary waves | They are slower than P-waves, so they are the second set of waves to be felt. |
Focus | Is usually several kilometers below Earths surface. |
Epicenter | Point on Earths surface directly above focus. |
Seismometers | Consist of a rotating drum covered with a sheet of paper, a pen or other such recording tool, and a mass, such as pendulum. |
Seismogram | Record produced by a seismometer. |
Richter scale | Devised by a geologist named Charles Richter, is a numerical rating system that measures the energy of the largest seismic waves. |
Magnitude | Produced during a earthquake. |
Amplitude | The largest seismic wave. |
Moment magnitude scale | Is a rating scale that measures the energy released by a earthquake, taking into account the size. |
Modified Mercalli scale | Which rates the type of damage they cause. |
Soil liquefaction | Vibrations can cause the ground to behave like a liquid in a phenomenon. |
Tsunami | A large ocean wave generated by vertical motions of the sea floor during an Earth quake. |
Seismic gaps | Are sections located along faults that are known to be active, but which have not experienced significant earthquakes for a long time. |