environmental hazard Flashcards
earthquake and volcanoes
what is a constructive plate?
This is where there are two plates moving away from each other causing new oceanic
crust to be formed.
what are destructive plate?
– This is where the plates move towards each other.
– The top layer of the mantle and the crust get dragged down beneath the continental
plate. The plate moves downwards very slowly at a rate of a few centimetres per year
what is a collision plate?
This is where two plates are moving together. The land is therefore buckled and pushed upwards forming high fold mountains.
what is a sliding plate?
This is where two plates slide past each other. The plates rub against each other
and, when the tension builds up, the pressure is released
what is the distribution of earthquakes and volcanoes?
Nearly all earthquakes/volcanic eruptions take place at or near plate boundaries. Here the earth is unstable. This is where crustal movement takes place. Volcanoes are found at constructive (where plates move apart) and destructive (where one plate is forced down below another) plate boundaries. This includes around The Pacific Ring of Fire around the Pacific Ocean. Magma is released to the surface at both of these boundaries. Earthquakes happen when pressure builds up between the plates. When the pressure becomes too high the plates suddenly slip causing an earthquake. This releases the pressure. This movement sends shock waves through the rocks.
