1.2 Causes of Earthquakes Flashcards
explain the Convection Currentscycle
Radioactive decay in the earth core causes the mantle to be heated at the base.
As the semi-molten rock in the upper mantle (asthenosphere) is heated it becomes less dense and rises towards the crust.
The magma is forces sideways as it can not pass through the solid rock above, this drags the plates sideways.
The magma cools nearer the crust so becomes more dense and sinks back down to the core to be re-heated.
The process of heating, rising, cooling and sinking forms currents within the magma called convection currents which drive plate movement.
what are the 4 types of plate boundries
destructive plate boundry
conservative plate boundry
constructive plate boundry
collision plate boundry
how do earthquakes occur on destructive plate boundaries?
earthquakes occur when one oceanic plate subductes under a continental plate because the oceanic is more dense. the friction for the 2 plates sliding cause a build up of pressure reasulting in the plates getting stuck. when too much pressure is built up the earthquake will jerk resulting in the plates being unstuck and releasing the pressure in the form of shock waves.
how do earthquakes occur on Conservative Plate Boundaries?
The plates sliding against eachother will create friction. The friction causes lots of pressure to build and after too much pressure the plates will become stuck. When the pressure becomes too much, the plates will slip realising shockwaves which we feel as earthquakes.
what happens at Conservative Plate Boundaries?
Two plates slide past one another either in opposite directions or same direction at different speeds (1).
What happens at destructive plate boundries?
The denser oceanic plate is forced under the less dense continental plate. The point where this occurs is called the subduction zone.
What happens at constructive plate boundries?
Two plates move apart from each other
How do earthquakes occur at constructive plate boundries?
When the plates move apart, the immense presure can result in sudden cracking of the crust which would reslease shockwaves that we feel as earthquakes
What happens at collison plate boundries?
Two continental plates move towards eachother creating fold mountains.
How do earthquakes occur at collison plate boundries?
the crashing of the Two continental plates colliding causes a lot of pressure which causes sudden cracking of the crust whic results in shockwaves which we feel as earthquakes.
what is a tectonic plate?
A giant slab of earth’s curst (1) which can move or float on top of the mantle (1)
