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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

disaster

a hazardous event that occurs over a limited time and in a defined geographic area

natural hazard

a natural process or event that is a potential threat to human life and/or property (human use of the land)

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

environmental unity

one action causes others in a chain of actions and events

forecast

statement that a particular event is likely to occur during a particular time interval

land-use planning

people can avoid building on areas where hazards are likely to occur

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)

prediction

determining the date, time, and size of an event using historical records, statistical analysis, weather conditions, and forecasting

risk

the product of the probability of that event occurring times the consequences should it occur

uniformitarianism

the idea that “the present is the key to the past” (processes that are occurring today have occurred in the past)

warning

occurs after a hazardous event has been predicted or a forecast has been made

fault

a plane of weakness in the earths crust

footwall

block below the fault plane where the miner would stand

hanging wall

block above the fault plane where a lantern can be hung

normal fault

downward movement of the hanging wall relative to the footwall

reverse fault

upward relative movement of the hanging wall due to compression

strain

change in shape or location of rocks due to applied stress

stress

a force that results from plate tectonic movements

strike-slip fault

offsets blocks of crust in a horizontal direction due to shearing stress

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

epicenter

the area at the surface directly above the focus

focus

the subsurface area along fault plane where motion and seismic waves begin

P waves

faster; travel through solids, liquids, and gases

S waves

slower; only moves through solids

paleoseismicity

the prehistoric record of earthquakes

seismic waves

elastic strain energy released from rocks breaking apart suddenly and violently at a fault

tectonic creep

gradual movement along a fault that is not accompanied by perceptible earthquakes

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

modified mercalli intensity scale

measures earthquake intensity

moment magnitude scale

measurement of the actual energy released during an earthquake

richter scale

first magnitude estimates are made

seismograph

records ground measure

fault scarp

low cliff which may extend for kilometers along the fault

liquefaction

Intense shaking can cause a near-surface layer of water-saturated sand to changerapidly from solid to liquid

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.

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.

crust

outermost layer of the earth

lithosphere

the rigid outer part of the earth, consisting of the crust and upper mantle

moho

boundary between earths crust and the mantle

continental drift

the gradual movement of the continents across the earth's surface through geological time

convergent boundary

plates pushing together

divergent boundary

plates pulling apart

mid-ocean ridge

underwater mountain range

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

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

transform boundary

places where plates slide past each other

triple junction

the point where the boundaries of three tectonic plates meet

hot spot

volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle

magnetic reversal

a change in a planet'smagnetic field such that the positions of magnetic north and magnetic south are interchanged

paleomagnetitism

the study of the record of the Earth's magnetic field in rocks, sediment, or archeological materials

crater

a bowl-shaped geological formation at the top of a volcano

decompression melting

occurs when the overlying pressure exerted on hot rock within the asthenosphere is decreased

effusive eruption

lava steadily flows out of the volcano onto the ground (more calm than explosive)

lava

magma that has reached the earths surface

magma

below or within the earths surface

magma chamber

large underground pool of liquid rock

pyroclastic debris

fragments blown out of a volcano by an explosive eruption

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

volcanic vent

an opening exposed on the earth's surface where volcanic material is emitted

caldera

a large volcanic crater, typically one formed by a major eruption leading to the collapse of the mouth of the volcano.

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

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

shield volcano

a broad, domed volcano with gently sloping sides; characteristic of the eruption of fluid; basaltic lava

stratavolcano

a volcano built up of alternate layers of lava and ash.

volcanic explosivity index

a relative measure of the explosiveness of volcanic eruptions

ash fall

a rain of airborne ash resulting from a volcanic eruption.

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.

lateral blast

a volcanic eruption that takes place on the flanks of a volcano instead of at the summit

lava flow

a mass of flowing or solidified lava

mudflow

a fluid or hardened stream or avalanche of mud

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

tephra

fragments of rock ejected from a volcano (usually very large)

why is history important when studying hazards?

hazards are repetitive events

5 fundamental concepts (general)

1. scientific method


2. risk


3. linkages


4. human ties


5. mitigation

what are natural service functions?

benefits of the event (ex: floods provide nutrient rich soil)

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)

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

surface waves

much slower than P and S waves, but cause much more damage

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

viscosity

resistance to flow in fluids

magma composition

how magma is melted (pressure and water)