| A | B |
|---|
| a fault | a break, or fracture, in the lithosphere |
| focus | point within the earth where an earthquake originates |
| epicenter | location on the surface of the earth directly above the focus |
| Elastic Rebound Hypothesis | states that most earthquakes are produced by the rapid release of energy stored in rocks when they've been subjected to forces that exceed their strength |
| elastic energy | type of energy stored in rocks during deformation |
| elastic rebound | when rocks spring back, causing slippage along a fault |
| foreshock | small releases of energy prior to an earthquake |
| aftershock | release of the last bit of elastic energy following an earthquake |
| primary, or p wave | type of seismic wave that travels as a compressional wave at a high rate of speed; can travel through all states of matter |
| secondary, or s wave | slower moving seismic wave that travels as a transverse wave; can only travel through solids |
| surface wave | most destructive of seismic waves; produced when body waves reach the surface |
| body wave | p and s waves |
| seismograph | instrument that records seismic waves |
| seismogram | digital, time record of ground motion from all 3 types of seismic waves |
| Mercalli Scale | refers to the intensity of shaking due to an earthquake; based on amount of damage |
| Richter Scale | old, log-based method of measuring the magnitude of an earthquake based on amplitude of the largest seismic wave |
| Moment Magnitude Scale | new method of measuring the strength of an earthquake based on estimated energy released from the rocks using fault displacement measurements |
| uplifting | vertical motion of the earth's surface |
| fault scarp | sharp-edged ridge formed by uplifting |
| offset | horzontal motion of the earth's surface |
| fault creep | slow, gradual movement of a fault |
| slip | short, sudden movement of a fault |
| liquefaction | uneven settling of structures due to effect of earthquake on heavily saturated soil and rock |
| tsunami | high energy wave formed when an earthquake pushes up a slab of ocean floor |
