Constructive Plate Boundaries
- Volcanoes and Earthquakes occur on constructive boundaries
- Constructive boundaries occur where two plates move apart
- Mantle under pressure from plates above and after movement this pressure is released
- The mantle melts because of this pressure producing magma
- Magma is less dense than plate so it rises above it to erupt and form volcanoes e.g. Helgafjell in Iceland
- EXAMPLE: Eurasian plate and North American Plate are moved apart at Mid Atlantic Ridge. Iceland has been formed because of the rising magma
- Some plates move faster than others which causes pressure to build up. Too much pressure causes fault lines. This fault line then causes an earthquake e.g. 2008 Iceland Earthquake
- At conservative boundaries, two plates get locked together which causes pressure to build up and therefore crack (fault is formed)
- E.g. the Pacific Plate is moving past the North American Plate resulting in the San Andreas Fault in California. Loma Prieta Eartquake 1989.
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