| A | B |
|---|
| Epicenter | Location on the surface of the Earth above the focus of the earthquake |
| Focus | The location where the rocks ruptured to produce the earthquake |
| Moment magnitude | A measure of the energy release by the earthquake |
| Based on the amplitude of the largstseismic wave produced in an earthquake | Richter Scale |
| Mercalli Scale | Qualitative scale to compare earthquakes based on shaking. |
| Interplate earthquake | Occurs within a single tectonic plate |
| Intraplate earthquake | Occurs between two tectonic plates |
| Fault | an occur when the stress on a rock exceeds the rock's strength |
| Seismic waves | Produced by a sudden rupture of therocks |
| Strike-slip fault | Sides of the fault displaced horizontally |
| Dip-slip fault | A fault with verticle displacement |
| Anticlines | Arc shapd folds in the rock |
| Synclines | Bowl shaped folds in therock |
| Past earthquake history | Paleoseismicity |
| P waves | Longtudinal compression waves |
| S waves | Tranverse shear waves |
| R waves | Surface waves |
| Seismogram | Written or digital record of an earthquake |
| Wave frequency | Measured in cycles per second |
| Strain | Deformation caused by stress |
| Tsunami wave | Produced by a sudden vertical displacement of ocean water |
| Forecast | Short term prediction |
| First stage of the earthquake cycle | Strain builds along a fault |
| Second stage of the earthquake cycle | Strain exceeds rock strength producing small quakes |
| Third stage of the earthquake cycle | Forescocks may be produced |
| Fourth stage of the earthquake cycle | Elastic rebound causing the major earthquake |
| Earthquake prediction | A subject of serious research |
