| A | B |
|---|
| fault | a break in Earth's crust where slabs of rock slip past each other |
| compression | the stress force that squeezes rock until if folds or breaks |
| earthquake | the shaking and trembling caused by movement of rock beneath the Earth's surface |
| stress | a force that acts on rock to change its shape or volume |
| deformation | any change in teh volumne or shape of the Earth's crust |
| tension | a stress force that pulls on the crust, stretching rock so it becomes thinner in the middle |
| normal fault | one block of rock, the hanging wall, lies above the fauly, while the other block, the footwall, lies below the fault |
| fault-block mountain | a mountain fomred when normal faults uplift |
| shearing | stress that pushes a mass of rock in two opposite directions |
| strike-slip fault | the rocks on either side of the fault slip past each other sideways |
| folds | bends in rocks that form when compression shortens and thickens part of Earth's crust |
| reverse faults | has the same structure as a normal fault, but the blocks move in the opposite direction |
| transform boundary | a plate boundary where two plates move past each other in opposite directions |
| plateau | a large area of flat land elevated high above sea level |
| friction | the force that opposes the motion of one surface as it moves across another surface |
| seismic waves | vibrations that travel through Earth carrying the energy released during an earthquake |
| the focus | the point beneath the Earth's surface where rock that is under stress breaks, triggering an earthquake |
| P waves | primary waves-the first waves to to arrive |
| S waves | secondary waves-they arrive after P waves |
| surface waves | P waves and S waves that reach the surface and produce the most severe ground movements |
| magnitude | a measurement of earthquake strength based on seismic waves and movement along faults |
| Mercalli Scale | a scale that rates earthquakes according to their intensity-the strength of ground motion in a certain place |
| Richter Scale | a scale rating the size of the seismic waves as measured by a mechanical seismograph |
| Moment Magnitude Scale | a rating system that estimates the total energy released by an earthquake |
| epicenter | the point on the Earth directly above the focus |
| liquefaction | when an earthquake's violent shaking suddenly turns loose, soft soil into liquid mud |
| aftershock | an earthquake that occurs after a larger earthquake in the same area |
| tsunami | a large ocean wave that is triggered when an earthquake jolts the ocean floor, displacing a large amount of water |
| base-isolated building | a building designed to reduce the amount of energy that reaches a building during an earthquake |
| creep meter | a fault monitoring device that uses a wire stretched across a fault to measure horizontal movement of the ground |
| laser-ranging device | a device which uses a laser beam to detect even tiny fault movements |
| tiltmeter | a device that measure tilting of the ground |
| satellite montors | satellites equipped with rader to make images of faults |
