Chapter 19
Tsunami
A large ocean wave generated by vertical motions of the sea floor during an earthquake
Moment Magnitude Scale
A rating scale that measures the energy released by an earthquake
Fault
Any fracture or system of fractures along which Earth moves
Soil Liquefaction
Areas with sand that is nearly saturated with water, seismic vibrations can cause the ground to behave like a liquid
Elastic Deformation
Caused when a material is compressed, bent, or stretched
Richter Scale
Devised by a geologist named Charles Richter, is a numerical rating system that measures the energy of the largest seismic waves
Seismometers
Instrument used to measure horizontal or vertical motion during an earthquake
Magnitude
Measure of the energy released during an earthquake, which can be described using the Richter scale
Modified Mercalli Scale
Rates the types of damage and other effects of an earthquake as noted by observers during and after it's occurrence
Seismogram
Record produced by a seismometer that can provide individual tracking of each type of seismic wave
Seismic Gaps
Sections located along faults that are known to be active, but which have not experienced significant earthquakes for a long period of time
Secondary Waves
Seismic wave that causes rock particles to move at right angles to the direction of the wave, known as an S-wave
Primary Waves
Squeeze and push rocks in the direction along which the waves are traveling
Strain
The deformation of materials in response to stress
Epicenter
The point on Earth's surface directly above the focus
Focus
The point where the waves originate
Amplitude
The size of the seismic waves; an increase of 1 in the scale represents an increase in amplitude of a factor of 10
Stress
The total force acting on crustal rocks per unit area
Seismic Waves
The vibrations of ground produced during an Earthquake
Plastic Deformation
When stress builds up past a certain point, called the elastic limit