Global Hazards Flashcards
Hotspot…
A hot plume of magma rising. Causes cracks in the lithosphere and creates chains of volcanoes.
Lahar…
A type of mudflow due to volcanic eruptions.
Lithosphere…
The rigid outer part of the earth, consisting of the crust and upper mantle.
Mid-oceanic ridge…
2 plates gone away from each other underwater.
Pyroclastic flow…
A current of hot gas and volcanic matter. Temperatures of 1000 degrees.
Oceanic crust…
Thinner and denser falling 6km.
Continental crust…
Thicker 10km less dense.
Mantle…
Semi-molten liquid, the earths float, heat from core. 2900km magma.
Outer core…
Dense. Iron& nickel. Semi liquid.
Inner core…
Solid. Extreme pressure. Everything is pushed into it.
Slab pull…
Old crust is cooler and thicker than the mantle, so it sinks into the mantle.
Ridge pull…
New crust rises because it is warm and thin, creating a ridge. Pushes old crust away.
Ring of fire…
Around Pacific Ocean home to 80% of the worlds active volcanoes.
Destructive margin…
Ocean crust falling. Continental pushing it under.
Destructive margin…
Oceanic crusts moving apart.
Conservative margin…
2 continental plates rubbing against each other. Violent quakes.
Collision margin…
Continental pushing into each other and one falling causing fold mountains.
Shallow focus quake…
Closer to surface. 0-70km. Waves radiate horizontally. Magnitude 1-5. common. Widespread.
Deep focus quake…
Away from surface. 70-700km. Magnitude 6-8. Waves radiate vertically. Rare. Localised.
P waves…
S waves…
P waves go through everything. S waves only go through solids.
Love waves…
Rayleigh waves…
Side to side. More damage.
Straight through.
Focus…
Where earthquakes begin. Seismic waves move out from this point.
Epicentre…
A point on the surface directly above the focus.
Seismic waves…
Waves of energy caused by sudden movement within the earth.
Aftershocks…
Pieces of earths crust and uppermost mantle which move causing aftershocks.
Richter scale…
Seismograph. Scientific. Each number 10x bigger.
Mercalli scale…
Questionnaire. Opinions.
Shield volcanoes…
Fatter. Shorter. Lava-runny. Constructive. Smaller no trapped air. Runny lava.
Compositive volcanoes…
Tall. Thin. Steep slope. Lava- thick. Ash. Destructive. Large- trapped air due to thick lava.
Nepal, Kathmandu…
25th April 2015.
Magnitude 7.8.
8(mercalli scale)
Shallow focus.
Mitigation method…
Building to survive future quakes. Base insulator- absorbs waves.
Cross hatching- strength.
