Question | Answer |
plate | a large section of earths crust and rigid upper mantle that moves around on the athenosphere. |
fault | surface along which rocks move when they pass their elastic limit and break. |
earthquake | vibrations produced when rocks break along a fault. |
normal fault | break in rocks caused by tension forces, where rock above the fault surface moves down realative to the rock below the fault surface. |
reverse fault | break in rock caused by compressive forces, where rock above the fault surface moves upward. |
strick-spil fault | break in rock caused by shear forces, where rocks move past each other without much vertical movement. |
wave | rythmic movement that carries energy through matter and space. |
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-and-down in a backward rolling motion and side-to-side in a swaying motion. |
epicenter | point on Earth's surface directly above an earthquake's focus. |
seismorgraph | instrument used to register earthquake waves and record the time that each arrived. |
crest | the highest point of a wave. |
magnitude | measure of the energy released durring an earthquake. |
liquefaction | occurs when wet soil acts more like a liquid durring an earthquake. |
tsunami | sesimic sea wave that begins over an earthquake focus and can be highly destructive when it crashes on shore. |