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82 Cards in this Set
- Front
- Back
catastrophe |
a massive disaster that requires significant expenditure of money and a long time for recovery |
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disaster |
a hazardous event that occurs over a limited time and in a defined geographic area |
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natural hazard |
a natural process or event that is a potential threat to human life and/or property (human use of the land) |
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geologic cycle |
Geological conditions and materials impact type, location, and intensity of natural processes. All physical, chemical, and biological processes on earth are referred to as the geologic cycle |
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environmental unity |
one action causes others in a chain of actions and events |
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forecast |
statement that a particular event is likely to occur during a particular time interval |
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land-use planning |
people can avoid building on areas where hazards are likely to occur |
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magnitude-frequency concept |
The impact of a hazardous event is in part a function of the amount of energy released (magnitude) and the interval between occurrences (frequency) |
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prediction |
determining the date, time, and size of an event using historical records, statistical analysis, weather conditions, and forecasting |
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risk |
the product of the probability of that event occurring times the consequences should it occur |
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uniformitarianism |
the idea that “the present is the key to the past” (processes that are occurring today have occurred in the past) |
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warning |
occurs after a hazardous event has been predicted or a forecast has been made |
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fault |
a plane of weakness in the earths crust |
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footwall |
block below the fault plane where the miner would stand |
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hanging wall |
block above the fault plane where a lantern can be hung |
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normal fault |
downward movement of the hanging wall relative to the footwall |
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reverse fault |
upward relative movement of the hanging wall due to compression |
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strain |
change in shape or location of rocks due to applied stress |
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stress |
a force that results from plate tectonic movements |
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strike-slip fault |
offsets blocks of crust in a horizontal direction due to shearing stress |
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earthquake cycle |
The earthquake cycle proposes that there is a drop in elastic strain after an earthquake and an accumulation of strain before the next event |
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epicenter |
the area at the surface directly above the focus |
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focus |
the subsurface area along fault plane where motion and seismic waves begin |
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P waves |
faster; travel through solids, liquids, and gases |
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S waves |
slower; only moves through solids |
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paleoseismicity |
the prehistoric record of earthquakes |
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seismic waves |
elastic strain energy released from rocks breaking apart suddenly and violently at a fault |
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tectonic creep |
gradual movement along a fault that is not accompanied by perceptible earthquakes |
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material amplification |
as P and S waves slow down, the energy that was once directed forward is transferred to the vertical motion of the surface waves |
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modified mercalli intensity scale |
measures earthquake intensity |
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moment magnitude scale |
measurement of the actual energy released during an earthquake |
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richter scale |
first magnitude estimates are made |
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seismograph |
records ground measure |
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fault scarp |
low cliff which may extend for kilometers along the fault |
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liquefaction |
Intense shaking can cause a near-surface layer of water-saturated sand to changerapidly from solid to liquid |
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asthenosphere |
the upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur. |
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convection |
the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat. |
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crust |
outermost layer of the earth |
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lithosphere |
the rigid outer part of the earth, consisting of the crust and upper mantle |
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moho |
boundary between earths crust and the mantle |
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continental drift |
the gradual movement of the continents across the earth's surface through geological time |
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convergent boundary |
plates pushing together |
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divergent boundary |
plates pulling apart |
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mid-ocean ridge |
underwater mountain range |
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seafloor 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 |
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subduction zone |
two oceanic lithospheric plates collide, one plate subducts beneath the other and a subduction zone and arc-shaped chain of volcanoes known as an island arc are formed |
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transform boundary |
places where plates slide past each other |
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triple junction |
the point where the boundaries of three tectonic plates meet |
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hot spot |
volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle |
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magnetic reversal |
a change in a planet'smagnetic field such that the positions of magnetic north and magnetic south are interchanged |
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paleomagnetitism |
the study of the record of the Earth's magnetic field in rocks, sediment, or archeological materials |
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crater |
a bowl-shaped geological formation at the top of a volcano |
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decompression melting |
occurs when the overlying pressure exerted on hot rock within the asthenosphere is decreased |
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effusive eruption |
lava steadily flows out of the volcano onto the ground (more calm than explosive) |
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lava |
magma that has reached the earths surface |
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magma |
below or within the earths surface |
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magma chamber |
large underground pool of liquid rock |
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pyroclastic debris |
fragments blown out of a volcano by an explosive eruption |
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volatiles |
the group of chemical elements and chemical compounds with low boiling points that are associated with a planet's or moon's crust and/or atmosphere |
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volcanic vent |
an opening exposed on the earth's surface where volcanic material is emitted |
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caldera |
a large volcanic crater, typically one formed by a major eruption leading to the collapse of the mouth of the volcano. |
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cinder cone |
built up by the accumulation of tephra near a volcanic vent; relatively small and composed of nut to fist size pieces of vesicular red or black lava |
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lava dome |
highly viscous felsic magma and are common along the ring of fire; relatively small and have low to moderate volatile content; very hazardous |
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shield volcano |
a broad, domed volcano with gently sloping sides; characteristic of the eruption of fluid; basaltic lava |
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stratavolcano |
a volcano built up of alternate layers of lava and ash. |
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volcanic explosivity index |
a relative measure of the explosiveness of volcanic eruptions |
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ash fall |
a rain of airborne ash resulting from a volcanic eruption. |
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debris flow (mudslide) |
a moving mass of loose mud, sand, soil, rock, water and air that travels down a slope under the influence of gravity. |
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lateral blast |
a volcanic eruption that takes place on the flanks of a volcano instead of at the summit |
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lava flow |
a mass of flowing or solidified lava |
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mudflow |
a fluid or hardened stream or avalanche of mud |
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pyroclastic flow |
a dense, destructive mass of very hot ash, lava fragments, and gases ejected explosively from a volcano and typically flowing downslope at great speed |
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tephra |
fragments of rock ejected from a volcano (usually very large) |
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why is history important when studying hazards? |
hazards are repetitive events |
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5 fundamental concepts (general) |
1. scientific method 2. risk 3. linkages 4. human ties 5. mitigation |
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what are natural service functions? |
benefits of the event (ex: floods provide nutrient rich soil) |
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what type of stresses are responsible for normal, reverse, and strike-slip faulting? |
normal: tensional stress (pulling apart) reverse: compressional stress (pushing together) strike-slip: shearing stress (sliding past) |
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how would you tell the difference between a strike-slip and a dip-slip fault? |
strike-slip is horizontal caused by shearing stress; dip-slip is vertical caused by tensional and compressional stress |
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surface waves |
much slower than P and S waves, but cause much more damage |
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how does the depth of an earthquakes focus relate to shaking and damage? |
the deeper the focus, the less shaking at the surface; energy is lost before seismic waves reach the surface |
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viscosity |
resistance to flow in fluids |
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magma composition |
how magma is melted (pressure and water) |