| A | B |
|---|
| fault | surfaces along which rocks break and move |
| earthquake | the movement of the ground caused by waves from energy released as rocks move along faults |
| normal fault | pull-apart fracture in rocks |
| reverse fault | a compression fracture in rocks |
| strike-slip fault | a break in rocks due to shearing forces |
| seismic wave | when the energy waves move outward from the earthquake focus |
| focus | the point where the earthquake energy is released |
| primary wave | waves of energy realeased during an earthquake that cause particles in rocks to compress and stretch apart |
| secondary wave | waves of energy that cause particles to move at right angles to the direction of the wave |
| epicenter | the point on the Earth's surface directly above an earthquake's focus |
| surface wave | waves that travel outward from the epicenter and travel in all directions |
| inner core | dense, solid center of Earth |
| outer core | liquid layer of Earth's core, made of nickel and iron |
| mantle | Thickest layer, lies between the outer core and crust; plasticlike |
| crust | outermost layer of Earth, 5 to 60 km thick |
| Moho discontinuity | the boundary between Earth's crust and the mantle |
| seismologist | a scientist that studies earthquakes |
| seismograph | an instrument used by seismologists to record waves of earthquakes |
| magnitude | measure of energy released by an earthquake by the Richter scale |
| tsunamis | an ocean wave that begins over an earthquake focus and can be up to 30m high |
| elastic limit | an earthquake occurs when the buildup of stress in the Earth's crust has reached the ____________ |
| convergent plate boundary | where a reverse fault is often located |
| divergent plate boundary | where rocks are subject to the force of tension |
| asthenosphere | primary and secondary waves slow down when they hit the |
| slowest waves | surface waves |
| shadow zone | the area between 105-140 degrees from an earthquake's focus |
| compression forces | generated at convergent plate boundaries |
