Tectonics Key Words Flashcards
Ash
The powdery residue left after the burning of a substance, usually molten rock
Asthenosphere
Upper part of the mantle below the lithosphere on which the plates float and where the rock is semi molten
Benioff zone
The zone of subduction where friction is created between colliding tectonic plates resulting in intermediate and deep earthquakes
Collision plate margin
When two continental plates come together and collide very slowly
-likely to cause folding and faulting of crustal rocks
Convergent plate margin
When an oceanic and continental plate come together usually resulting in subduction of the denser plate
-creates surface features such as a trench and deep features such as a Benioff zone
Composite cone volcano
A narrow based steep sided volcano made of alternating layers of ash and lava. They usually have andesitic lava leading to sudden and violent explosions
Conservative plate margin
When two plates slide past each other or in the same direction and different speeds
-friction between the two plates is great and stresses and strains build up to create shell earthquake foci
Divergent plate margin
When two plates more apart from each other often leading to the creation of shield volcanos
Crustal fracturing
When energy released during an earthquake causes the earth’s crust to crack
Earthquake seismic energy
Energy released in the form of P, S and L waves from the hypocentre of the earthquake
Elastic energy
When a plate is sub-ducted it’s original shape is warped, eventually the elastic energy of the plate exceeds the strength of the plate above it causing it to flip
Epicentre
The point directly above the hypocentre on the surface where the mot shaking and seismic energy is felt
Focal depth
The distance between the hypocentre and the surface of the earth. Deeper hypocentre tends to creates less shaking due to the seismic waves having to travel through more of the earth leading to greater energy reduction
Hot spot volcano
when magma from a magma plume find and forces it way through a crack in the middle of the plate often leading to creation of shield volcanos
Hydrometerological hazards
Natural hazards caused by climatic processes like droughts, floods, hurricanes and storms
Hypocentre
The point in the earth from which pressure is released and where seismic waves come from
Intensity
The relative damage or energy released by a hazard, measure by a scale (e.g. VEI or MMS)
Intraplate
A crack of fault which extends into a plate away from a boundary
Jokulhlaups
An Icelandic term to describe glacial outburst or floods by the destruction of a natural dam
Lahar
Saturated soil infused with ash forming a channel of mud slides that resemble a landslide
Landslide
A mass movement of rock and soil down a steep slope under the influence of gravity, perhaps triggered by and earthquake loosening material
Community adaption
People within communities, either whole or parts of settlements , work together to change their way of life so that the impact of a tectonic event isn’t as hazardous