| A | B |
|---|
| Earthquake | the shaking or trembling caused by the sudden release of energy; usually associated with faulting or breaking of rocks |
| Aftershock | due to an earthquake; continuing adjustment of position |
| Elastic Rebound Theory | explains how energy is stored in rocks; rocks bend until the strength of the rock is exceeded |
| Focus | point within Earth where faulting begins (hypocenter) |
| Epicenter | point directly above the focus on the surface |
| Seismology | study of data recorded with the earthquake |
| Beinoff Zone | at convergent boundaries, focal depth increases along a dipping seismic zone |
| Circum-Pacific Belt | 80% of earthquakes occur here |
| Mediterranean-Asiatic Belt | 15% of earthquakes occur here |
| Primary Wave | body wave; fastest waves that travel through solids, liquids, or gases; compressional wave |
| Compressional Wave | material movement is in the same direction as wave movement |
| Secondary Wave | body wave; slower thank P waves; travel through solids only; shear wave |
| Shear Wave | move material perpendicular to wave movement |
| Surface Wave | travel below or along the ground's surface; slower than body waves; rolling and side to side movement esp. damage to buildings |
| P waves, S waves, then L and R | seismic wave behavior |
| Difference in arrival times at a seismograph station | after an earthquake, can be used to calculate the distance from the seismograph to the epicenter |
| Time-distance Graph | shows the average travel times for P and S waves |
| 3 | amount of seismograph stations needed to locate the epicenter of an earthquake |
| Intensity | subjective measure of the kind of damage done and people's reactions to it |
| Isoseismal lines | identify areas of equal intensity |
| Richter Scale | measures total amount of energy released by an earthquake; independent of intenstiy |
| Logarithmic Scale | amplitude of the largest wave produced by an event is corrected for distance and assigned a value on an open-ended_____. |
| Ground Shaking | amplitude, duration, and damage increases in poorly consolidated rocks |
| Destructive Effects of Earthquakes | building collapse, fire, tsunami, ground failure |
| Earthquake Precursors | changes in elevation or tilting of land surface, fluctuations in groundwater levels, magnetic field, electrical resistance of the ground |
| Earthquake Prediction Programs | include laboratory and field studies of rocks before, during, and after earthquakes, monitor activity along major faults, produce risk assessments |
| Velocity of waves | dependent on the density and elasticity of material they travel through |
| Discontinuities | the basis for subdividing Earth's interior into concentric layers |
| P waves | indicate a solid inner core (iron/nickel,rotates more rapidly than outer core) |
| S waves | indicate a liquid outer core(iron mixed w/sulfur VERY dense 9.9 to 12.3 g/cm3) |
| Moho | separates the crust from the mantle |
| Low velocity zone | part of the mantle inferred to represent zones of partial melting in the asthenosphere |
| Composition of mantle | igneous rock peridotite |
| Continental Crust | granite composition, low density, averages 35 km thick; mathic magma |
| Oceanic Crust | gabbro/basaltic composition, higher density, between 5 and 10 km thick |
| Geothermal Gradient | temp increases with depth, avg 25 deg C/km, most heat generated by radioactive decay |
