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chapter8&10vocabular
| Term | Definition |
|---|---|
| earthquake | movements of the ground due to sudden release of energy |
| focus | point in the earths interior where the earthquake occured |
| seismic waves | waves of energy released by an earthquacke |
| epicenter | point on earths surface directly above the focus |
| elastic rebound | sudden return of deformed rock back to undeformed shape |
| body waves | seismic waves that move through the inside of earth |
| p waves | push-pull body waves |
| s waves | side-to-side body waves |
| surface waves | seismic waves that move on the earths surface |
| seismograph | all seismic waves are recorded |
| seismogram | pen traces vibration onto a moving drum of paper |
| richter scale | numerical scale based on height of largest seismic wave |
| moment magnitude scale | measures the amount of energy released |
| modified mercalli scale | roman numeral scale that measures the intensity created by an earthquake |
| loquefaction | process that generates a liquid from a solid or a gas |
| tsunami | a long high sea wave caused by an earthquake |
| seismic gap | a segment of an active fault known to produce significant earthquake that has not slipped in an unusually long time |
| continental drift | the gradual movement of the continents across the earths surface through geological time |
| Alfred Wegener | german geophysicist who proposed the theory of continental drift |
| Pangaea | hypothetical supercontinent that included all current land mass |
| sonar | a system for the detection of objects under water and for measuring the water depth by emitting sound pulses and detecting or measuring their return after being reflected |
| deep-ocean trench | any long narrow steep-side depression in the ocean bottom in which occur the maximum oceanic depths |
| mid-ocean ridge | a long seismically active ridge system situated in the middle of the ocean basin and marking the site of the upwelling of magma associated with seafloor spreading |
| rift valley | a large elongated depression with steep walls formed by the downward displacement of a block of the earths surface between nearly parallel faults or fault system |
| sea-floor spreading | the formation of new areas of oceanic crust which occurs through the upwelling of magma at midocean ridges and its subsequent outward movement on either side |
| subduction | the sideways and downward movement of the edge of a plate of the earths crust into the mantle beneath another plate |
| subduction zone | plate tectonics boundaries where two plates converge and one plate is thrust beneath the other |
| normal polarity | where the magnetic north points towards the geographic north pole |
| reverse polarity | the north end of the magnetic field is close to the present day south pole |
| paleomagnetism | the branch of geophysics concerned with the magnetism in rocks that was induced by the earths magnetic field at the time of their formation |
| plate | the two sub-layers of the earths crust that move float and sometimes fracture |
| asthenosphere | the upper part of the earths mantle |
| plate tectonics | a theory explaining the structure of the earths crust |
| divergent boundary | a tectonic boundary where two plates are moving away from each other and new crust is forming from magma that rises to the earths surface between two plates |
| convergent boundary | a tectonic boundary where two plates towards each other |
| transform fault boundry | places where plates slide sideways past each other |
| continental volcanic arc | type of volcanic arc occurring a "arc-shaped" topographic high region along a continental margin |
| volcanic island arc | a curved chain of volcanoes in the overriding tectonic plate of a subduction zone |
| convection currents | a current in a fluid that results from convection |
Created by:
2007010
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