Earthquake and Fault Vocabulary

amplitude
Height of the wave
compression
A squeezing force.
epicenter
Point on the Earth's surface above where the earthquake waves originate.
fault
A break in the Earth's surface along which movement occurs.
focus
Point below the surface where the earthquake waves originate.
frequency
The number of back-and-forth cycles per second, in a wave or wave-like process.
longitudinal waves
Wave in which the individual particles of a medium vibrate back and forth in the direction in which the wave travels
Mercalli scale
Scale (from I to XII) to measure the amount of damage caused by an earthquake.
normal fault
Type of fault resulting from tension.
period
The time for one wavelength to pass a point.
primary waves
Seismic waves that shakes the ground back and forth in the same direction as the direction the wave is moving.
reflection
The change in direction (or return) of waves striking a surface.
refraction
Waves change direction as they pass from one medium to another.
reverse fault
Type of fault resulting from compression forces.
Richter scale
A numeric scale to measure ground motion.
secondary wave
Seismic waves that shakes the ground back and forth perpendicular to the direction the waves are moving.
seismogram
Visual display of ground motion versus time.
seismograph
Device for measuring ground motion.
shear
A force that causes two adjacent parts of a body to slide past each other.
strike-slip fault
Type of fault resulting from shearing forces.
surface waves
Seismic waves that travel along the outer layers of the earth.
tension
A pulling force.
transverse waves
Wave in which the vibrations of the medium are perpendicular to the direction the wave is moving.
wave
Rhythmic disturbance that transfers energy from place to place.