| 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 until it folds or breaks |
| shearing | stress that pushes masses of rock in opposite directions, in a sideways movement |
| normal fault | a type of fault wehre the hanging wall slides downward caused by tension in the crustst |
| hanging wall | the block of rock that forms the upper half of a fault |
| footwall | the block of rock that forms the lower half of a fault |
| reverse fault | a type of fault where the hanging wall slides upwards: caused by compression in the crust |
| strike-slip fault | a type of fault in which 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 in Earth's crust |
| plateau | a large area of flat land elevated high above sea level |
| earthquake | the shaking that results from the movement 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 compresses and expands the ground |
| S wave | a type of seismic wave that moves the ground up and down or side to side |
| surface wave | a type of seismic wave that forms when P waves and S waves reach Earth's surface |
| mercalli scale | a scale that rates earthquakes accoring to their intensity and how much damage they cause at a particular place |
| magnitude | the measurement of an earthquake's strength based on seismic waves and movement along faults |
| richter scale | a scale that rates an earthquake's magnitude based on the size of its seismic waves |
| 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 |
| base-isolated building | a building mounted on bearings designed to absorb the energy of an earthquake |
