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why do volcanoes and earthquakes occur at plate boundaries

Destructive plate margins Pare where a plate of higher density isP subducted,
or forced underneath,Panother, less dense plate. This occurs due to convection currents in the mantle. These are caused by radioactive decay which produces heat, causing the hotter, less dense material to rise and then sink when it cools down again (like the heating of a room by a radiator). u Volcanoes /u Melting of the mantle occurs above the subducted plate.


The magms (melt) is less dense, so it rises up towards the crust. The magma pushes through the crust, and erupts at the earth #39;s surface as a volcano. This can be very explosive (example, Mount St Helens eruption, May 1980). u Earthquakes /u As the plate is being subducted, it can sometimes become stuck on the overriding plate. The subducting plate is still trying to force its way down into the mantle, so there is a build up of force.


This can also drag the overriding plate down with it (a good way to visualise this is to use your hands as the plates and see what happens when one gets #39;stuck #39;). If enough force builds up, this causes the plates to jolt suddenly past each other, with the overriding plate pinging back up. This releases energy, which is felt as an earthquake. Oceanic plates occur under the oceans. Continental plates form the land.


Oceanic plates are denser than continental plates. They are pushed down underneath continental plates if they meet. Where tectonic plates meet, the Earths crust becomes unstable as the plates slide past each other, push against each other, or ride under or over one another. Earthquakes and volcanic eruptions happen at the boundaries between plates. Magma (molten rock) is less dense than the crust. It can rise to the surface through weaknesses in the crust, forming a volcano.


Geologists study volcanoes to try to predict future eruptions. Volcanoes can be very destructive, but some people choose to live near them because volcanic soil is very fertile. The movement of tectonic plates can be sudden and disastrous, causing an earthquake. It is difficult to predict exactly when and where an earthquake will happen, even when a lot of data is available. Now try a.

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