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where is the "ring of fire"
circum-Pacific belt. where 80% of earthquakes take place
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what is the theory on how equakes are made?
Elastic Rebound Theory(rocks break if strained too much)
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define P waves
primary waves-fastest waves and can travel through any substance
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def S waves
slower than P and can't travel through liquids(only solids)
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def surface waves
slowest and travel on the earths surface and the MOST DESTRUCTIVE
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how do you measure an earthquake?
- Intensity=measure of destruction(Modified Mercallie scale)
- Magnitude=measure of energy released(richter scale)
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name 5 common destructive properties of equake
- Ground Shaking
- Soil Liquefaction(quicksand/liquefying effect)
- Fire
- Tsunami
- Ground failure(slumps/landslides)
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what type of predictions do we have that an earthquake will happen
- short temr: strange behaviour of animals, dilation of rock
- long term: seismic gaps(areas of reduced earthquake activity
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who is alfred wegener?
developed theory of continental drift in 1915 and named pangea
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what are zones of pangea
- Gondwanaland=southern landmass
- Laurasia=northern landmass
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what evidence do we have of the continental drift
Paleomagnetism(rock layers match up on both continents)
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what happens to the divergent plate boundaries
- Forces: tensional or extensional
- Lnadforms: oceanic ridges, rift valleys, horsts and grabens
- Faults: normal faults
- Shallow focus earthquakes
- EX: north america plate, eurasian plate, south america plate, africa plate
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what happens at convergent plate boundaries(subduction zone)?
- Forces: compressional(orogenisis is mountain building)
- Landforms:mountains, volcanic arcs, island arcs, folded mountains and folds
- Faults:thrust faults and reverse faults
- shallow to deep focus of equakes
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examples of convergent boundary places
- ocean to ocean: island arcs, japan
- ocean to continent: volcanic arcs,cascades and andes
- continent to continent: forlded mountains,himalayas, alps
- juan de fuca plate, north america plate, nazca plate, south america plate
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what happens at transform plate boundaries
- Forces: shear
- Landforms: offset drainage, linear valleys, and sag ponds
- Faults: strike slip faults
- Shallow focus earthquakes
- EX:pacific plate, north america plate(san andreas fault)
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what moves the plates
convection currents produced by radiogenic heat
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