| A | B |
|---|
| New Madrid fault | a major seismic zone in the Southern & Midwestern US stretching to the SW from New Madrid, Missouri. Responsible for the 1812 earthquake. Has potential to produce earthquakes every 300-500 years |
| normal fault | break in rock caused by tension forces, where rock above the fault surface moves down relative to the rock below the fault surface |
| reverse fault | break in rock caused by compressive forces, where rock above the fault surface moves upward relative to the rock below the fault surface |
| strike-slip fault | break in rock caused by shear forces, where rocks move past each other without much vertical movement |
| seismic wave | wave generated by an earthquake |
| focus | in an earthquake, the point below Earth's surface where energy is released in the form of seismic waves. |
| primary wave | seismic wave that moves rock particles back and forth in the same direction that the wave travels |
| secondary wave | seismic wave that moves rock particles at right angles to the direction of the wave |
| surface wave | seismic wave that moves rock particles up & down in a badkward rolling motion and side to side in a swaying motion |
| epicenter | point on Earth's surface directly above an earthquake's focus |
| seismograph | instrument that measures earthquake waves and records the time that each arrived |
| magnitude | measure of the energy released during an earthquake |
| liquefaction | occurs when wet soil acts more like a liquid during an earthquake |
| tsunami | seismic sea wave that begins over an earthquake focus and can be highly destructive when it crashes on shore |
| elastic deformation | This happens to rocks when an applied force causes rocks to bend and stretch |
| elastic limit | the point at which any additional force will permanently deform the object's shape |
| moho | short for "Mohorovivic Discontinuity"... the boundary between the crust and the mantle of the earth |
| modified mercalli intensity scale | scale used to measure the intensity of a earthquake on a 1-12 scale. 1 is the weakest, 12 is the strongest |
