| base-isolated building | building mounted on bearings designed to obsorb the energy of an earthquake |
| tsunami | a giant wave caused by an earthquake on the ocean floor |
| creep meters | measures horizontal movement |
| laser-ranging device | device that bounces laser beams off a reflector to detect fault movements |
| tiltmeter | device that measures vertical movements |
| S waves | type of seismic wave that moves the ground up and down or side to side |
| tension | stress that stretches rock so that it becomes thinner in the middle |
| shearing | stress that pushes a mass of rock in opposite directions |
| compression | stress that squeezes rock until it folds or breaks |
| deformation | a change in volume or shape of earth's crust |
| fault | a break in earth's crust where slabs of rock slip past each other |
| strike-slip fault | type of fault where rocks on either side move past each other side ways in a little up and down motion |
| normal fault | type of fault where the hanging wall slides downwards caused by tension |
| reverse fault | type of fault where the hanging wall slides upward |
| footwall | block of rock that forms the lower half of the fault |
| fault-block mountain | mountain that forms where a normal fault uplifts a block of rock |
| stress | force that acts on rock to change its shape or volume |
| magnitude | measurement of an earthquake's strength based on seismic waves and movement along faults |
| seismograph | device that records ground movemetns caused by seismic waves as they move through Earth |
| moment-magnitude scale | scale that rates earthquakes by estimating the total energy released by an earthquake |
| P waves | type of seismic wave that compresses and expands the ground |
| hanging wall | block of rock that forms the upper half of a fault |
| Mercalli Scale | scale that rates earthquakes according to their intensity and how much damage they cause |
| Richter Scale | a scale that rates seismic waves as measured by a particular ype of mechanical seismograph |
| epicenter | the point on Earth's surface directly above an earthquake's focus |
| focus | point beneath EArth's surface where rock breaks under stress and causes an earthquake |
| earthquakes | the shaking of the earth's crust |
| liquefaction | process by which an earthquake's violent movement suddenly turns into liquid mud |
| fold | bend in rock that forms where part of Earth's crust is compressed |
| anticline | upward fold in rock formed by compression of Earth's crust |
| syncline | downward fold in rock formed by compression in Earth's crust |
| plateau | landform that has a more or less level surface and is elevated high above sea level |
| satellite monitors | takes pictures of faults by using the radar |
| aftershock | an earthquake that occurs after an larger earthquake in the same area |