| A | B |
|---|
| stress | A force that acts on rock to change its shape or volume. |
| tension | Stress that stretches rock so that it becomes thinner in the middle. |
| compression | Stress that squeezes rock, making it thick in the middle. |
| shearing | Stress that pushes masses of rock in opposite directions, in a sideways movement. |
| normal fault | A type of fault caused by tension in the crust. |
| hanging wall | The block of rock that slides down in a normal fault. |
| footwall | The block of rock that slides down in a reverse fault. |
| reverse fault | A type of fault caused by compression in the crust. |
| strike-slip fault | A type of fault in which the rocks on either side move past each other sideways with little up or down motion. |
| anticline | An upward fold in rock formed by compression of Earth's crust. |
| syncline | A downward fold in rock formed by compression of Earth's crust. |
| fault-block mountain | A mountain formed when two normal faults are parallel to each other |
| earthquake | The shaking that results from the breaking of rock beneath Earth's surface. |
| focus | The point beneath Earth's surface where rock breaks under stress and causes an earthquake. |
| epicenter | The point on Earth's surface directly above an earthquake's focus. |
| P wave | A type of seismic wave that arrives first because it is the fastest. |
| S wave | A type of seismic wave that shakes the ground up and down or side to side. |
| surface wave | A type of seismic wave that causes the most damage. |
| Mercalli scale | A scale that rates earthquake damage. |
| magnitude | The measurement of an earthquake's strength based on seismic waves and movement along faults. |
| Richter scale | A scale that works well only for small, nearby earthquakes. |
| seismograph | A device that records ground movements caused by seismic waves as they move through Earth. |
| moment magnitude scale | A scale that rates earthquakes by estimating the total energy released by an earthquake. |
| seismogram | The record of an earthquake's seismic waves produced by a seismograph. |
| friction | The force that opposes the motion of one surface as it moves across another surface. |
| liquefaction | The process by which an earthquake's violent movement suddenly turns loose soil into liquid mud. |
| aftershock | An earthquake that occurs after a larger earthquake in the same area. |
| tsunami | A large wave produced by an earthquake on the ocean floor. |
| base-isolated building | A building mounted on bearings designed to absorb the energy of an earthquake. |
