| A | B |
|---|
| aftershock | a smaller earthquake that occurs after a larger earthquake |
| compression | a type of stress that squeezes rock, causing it to break or fold |
| earthquake | movement of the ground caused by the release of energy from a sudden shift of rocks in Earth's crust |
| epicenter | the point on Earth's surface directly above the focus of an earthquake |
| fault | a break in Earth's crust where movement of rock occurs |
| fault zone | a place along plate boundaries where many faults are located |
| focus | the point below Earth's surface where movement of rock produces an earthquake |
| foreshock | a small earthquake that precedes (comes before) a larger earthquake |
| magnitude | the measurement of the total strength or amount of energy released by an earthquake |
| Mercalli scale | a measurement of an earthquake's intensity based on how much damage it causes (Level I to Level XII) |
| movement magnitude scale | a measurement of an earthquake's magnitude based on the amount of movement along the rock fault line |
| normal fault | a type of fault where forces of tension are pulling rock apart |
| P (Primary) wave | the fastest moving type of seismic wave, which expands and compresses rock, like the movement in a slinky. (Pressure waves) They can travel through liquids and solids. |
| reverse fault | a type of fault where compression pushes rock together. Also known as a thrust fault. |
| Richter scale | a measurement of the magnitude of an earthquake based on the readings of a seismograph. (0-9 on a logarithmic scale) |
| S (Secondary) wave | the second-fastest moving type of seismic wave, which moves rock horizontally from side to side. (Shear waves) Cannot pass through liquids, not through Earth's liquid outer core. |
| seismic wave | a vibration that travels through Earth carrying the energy released during an earthquake |
| seismograph | an instrument that records seismic waves |
| shearing | a type of stress that pushes two adjacent areas of rock in opposite directions |
| stress | a force that causes rock to change shape |
| strike-slip fault | a type of fault where rocks slide horizontally past each other in opposite directions, with little up or down motion. |
| surface waves | seismic waves that move along Earth's surface; they can have an up-and-down motion or a horizontal motion. They travel slower than P and S waves and usually cause the most damage |
| tension | a type of stress that stretches rock and makes it thinner |
| tsunami | a giant, fast-moving wave that is caused by an undersea earthquake (seismic sea wave) |
