| A | B |
|---|
| Earthquake | Shaking and trembling hat results from the movement of the rock beneath the Earths surface |
| Stress | A force that acts on rock to change its shape or volume. |
| Shearing | Stress that pushes a mass of rock in two opposite directions. Can cause rock to break and slip apart or to change its shape. |
| Tension | Stress force that pulls on the crust and stretches the rock so it becomes thinner in the middle. |
| Compression | Stress force that squeezes rock until it folds or breaks. |
| Deformation | Any change in the volume or shape of the Earths crust |
| Fault | Break in the crust where slabs crust slip past each other. Occurs usually along plate boundaries where the forces of plate motion compress, pull, or shear the crust so much that the crust breaks. |
| Strike-slip fault | The rocks on either side of the fault slip past each other sideways with little up or down motions. |
| Normal fault | The fault is at an angle so one rock lies above the fault while the other block lies below the fault. |
| Hanging wall | The half of the fault that lies above the other block |
| Footwall | The other half of the fault that lies below. |
| Reverse fault | Has the same structure of a normal fault, but the blocks move in opposite directions. Compression forces produce reverse faults. |
| Fault block mountain | When normal faults uplift a block of rock |
| Folds | Bends in rock that forms when compression shortens and thickens part of the Earths crust. |
| Anticline | Fold in rock that bends upward into an arch |
| Syncline | Fold in rock that bends downward in the middle to form a bowl. |
| Plateau | A large area of flat land elevated high above sea level. |
| Focus | A point beneath Earths surface where rock that us under stress breaks, triggering an earthquake. |
| Epicenter | Point on the surface directly above the focus |
| Seismic waves | Vibrations that travel through Earth carrying the energy release during an earthquake. |
| P waves | Earthquake waves that compress and expand the ground like an accordion. Primary waves. |
| S waves | Earthquake waves that vibrate from side to side and are the second ones to arrve at a recording station |
| Surface waves | When p waves and s waves are transformed into surface waves. They move more slowly then p and s waves. |
| Seismograph | Records the ground movements cause by seismic waves as they move through the Earth. |
| Magnitude | Measurement of earthquake strength based on seismic wants and movement along faults. |
| Mercalli scale | Developed to rate earthquakes according to their intensity |
| Richter scale | Rating of the size of seismic waves as measures by a particular type of mechanical wave. |
| Moment magnitude scale | Rating system that estimates the total energy released by an earthquake. |
| Liquefaction | Occurs when an earthquakes violent shaking suddenly turns loose, soft soil into liquid mud. Likely where the soil if full of moisture. |
| Aftershock | An earthquake that occurs after a large earthquake in the same area. |
| Tsunamis | Water displaced by an earthquake that forms large waves |
| Base-isolating building | A building designed to reduce the amount of energy that reaches the building during an earthquake |
