| A | B |
|---|
| Stress | a force that acts on rock to change its shape or volume |
| Tension | stress force that pulls on the crust and thins rock in the middle |
| Compression | stress force that squeezes rock until it folds or breaks |
| Shearing | stress force that pushes rock in two opposite directions |
| Normal Fault | where rock is pulled apart by tension and the hanging wall moves down |
| Reverse Fault | where compression pushes rock together and the hanging wall moves up |
| Strike-slip Fault | where shearing pushes rock in opposite directions past each other with little up or down motion |
| Anticline | a fold in rock that bends or archs upward |
| Syncline | fold in rock that bends downward or sinks |
| Plateau | a large flat area of land elevated high above sea level |
| Earthquake | the shaking and trembling that results from movement of rock beneath Earth's surface |
| Focus | the area beneath Earth's surface where rock that was under stress begins to break and move |
| Epicenter | the point on the surface of the Earth directly above the focus |
| P Waves | seismic waves that compress and expand the ground like an accordian |
| S Waves | seismic waves that can vibrate side to side or up and down |
| Surface Waves | seismic waves that can make the ground roll like ocean waves |
| Seismograph | instrument that records and measures and earthquake's seismic waves |
| Modified Mercalli scale | scale that rates the amount of shaking from an earthquake without using any instruments |
| Magnitude | a single number geologists assign to an earthquake based on the earthquake's size |
| Richter scale | scale that rates the magitude of small earthqukes based on the size of the waves as recorded by seismographs |
| Moment Magnitude scale | scale that rates the total energy an earthquake releases |
| Seismogram | the record of an earthquake's seismic waves produced by a seismograph |
