Dear Student
Tectonic plate is a huge and irregularly shaped slab of rock which is composed of both continental and oceanic lithosphere. It is formed by the breaking of the crustal block due to the rising convention current from the mantle.
Most volcanic eruptions and earthquakes happen along the margins of tectonic plates because those margins are highly unstable. As the plates try to keep moving, immense amount of pressure builds up along these margins.This pressure eventually erupts as volcanic eruptions and earthquakes.
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