word | Definition |
faults | a large fracture in rocks, form several meters to many kilometers long, where rocks not only crack but also move along either side of the break. |
earthquakes | the movement of the ground, caused by waves from energy released as rocks move along faults |
normal fault | a pull-apart (tension) fracture in rocks, where rocks that are above the fault surface drop downward in relation to rocks that are below the fault surface. |
reverse fault | a compression fracture in rocks, where rocks that are above the fault surface are forced up over rocks that are below the fault surface. |
strike-slip fault | a break in rocks where rocks on either side of the fault move past each other (instead of above or below each other). |
seismic waves | the energy waves that make the ground quake during an earthquake |
focus | in a earthquake, the point in earth's interior where movement releases energy to cause the earthquake. |
primary waves | waves of energy, released during an earthquake, that travel through earth by compressing particles in rocks in the same direction the wave is traveling. |
secondary waves | waves of energy, released during an earthquake, that travel through earth by moving particles in rocks at right angels to the direction the wave is traviling |
epicenter | the point on earth's surface directly above an earthquake's focus |
surface waves | waves of energy, released during an earthquake, that reach Earth's surface and travel outward from the epicenter in all directions |
Moho discontinuity | the boundary between Earth's crust and the upper mantle; seismic waves travel slower above the Moho and faster below it. |
seimologists | a scientist who studies earthquakes and seismic waves |
seismograph | an instrument that records earthquake waves |
magnitude | in earthquake studies, a measure of the energy released by an earthquake |
tsunamis | an ocean wave caused by an earthquake |
seismic-safe | describes structures that are resistant to movements from an earthquake |