| A | B |
|---|
| compression | stress that SQUEEZES rock until it folds or breaks |
| earthquake | the SHAKING that results from the movement of rock beneath Earth's surface |
| epicenter | the POINT on Earth's surface directly ABOVE an earthquake's focus |
| fault | a break or CRACK in Earth's lithosphere along which the rocks move |
| focus | the point BENEATH Earth's surface where rock breaks under stress and causes an earthquake |
| fold | a BEND/fold in rock that forms where of of Earth's crust is compressed |
| footwall | the block of rock that forms the LOWER HALF of a fault |
| hanging wall | the block of rock that forms the UPPER HALF of a fault |
| magnitude | the measurement of an earthquake's STRENGTH based on seismic waves and movement along faults |
| Mercalli scale | a scale that rates earthquakes according to their INTENSITY and how much damage they cause |
| moment magnitude scale | a scale that rates earthquakes by estimating the total energy released by an earthquake |
| normal fault | a type of fault where the hanging wall slides DOWNWARD; caused by tension in the crust |
| P waves | a type of seismic wave that compresses and expands the ground |
| Pangaea | the name of the single landmass that broke apart 200 million years ago and gave rise to today's continents |
| plate boundaries | a crack in the lithospere where two of Earth's plates meet |
| plate tectonics | the theory/idea that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle |
| plateau | a landform that has a more or less level surface and is elevated high above sea level |
| plates | a section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust |
| reverse fault | a type of fault where the hanging wall slides UPWARD; caused by compression in the crust |
| Richter scale | a scale that rates seismic waves as measured by a particular type of mechanical seismograph |
| S waves | a type of seismic wave that moves the ground up and down or side to side |
| seismograph | a device that records ground movements caused by seismic waves as they move through Earth; used to detect and measure earthquakes. |
| shearing | stress that pushes a mass of rock in opposite directions |
| stress | a force that acts on rock to change its shape or volume |
| strike-slip fault | a type of fault where rocks on either side move past each other sideways with little up-or-down motion |
| surface waves | a type of seismic wave that forms when P waves and S waves reach Earth's surface |
| tension | Stress that stretches rock so that it becomes thinner in the middle |
