Science

Term Definition
Stress A force that acts on rock to change its shape or volume
Tension
Compression squeezes rock until it folds or breaks
Shearing Stress that pushes a mass of rock in two opposite directions
Normal Faults Tension in Earth's crust pulls rock apart
Hanging wall The block of rock that lies above
Footfall The block of rock that lies below
Reverse fault has the same structure as a normal fault, but the blocks move in opposite direction
Strike-Slip fault Rocks on either side of the fault slip past each other sideways,with little up or down motion
Anticline A fold in rock that bends upward into an arch
Syncline A fold in rock that bends downward to form a valley
Plateau A large area of flat land elevated high above sea level
Earthquake is the shaking and trembling that results from the movement of rock beneath Earth's surface
Focus is the area beneath Earth's surface where rock that is under stress breaks, triggering an earthquake
Epicenter The point on Earth's surface directly above the focus
P waves First waves to arrive
S waves After p waves comes secondary waves
Surface waves Move more slowly than P waves and S waves, but they can produce severe ground movements
Mercalli Scale was developed to rate earthquakes according to the level of damage at a given place
Magnitude Number that geologists assign to an earthquake based on the earthquake's size
Richter scale Rating of an earthquake's magnitude based on the size of the earthquake's seismic waves
Seismograph The seismic waves are measured by a seismograph
Moment Magnitude Scale A rating system that estimates the total energy released by an earthquake