Plate Boundaries

• Divergent boundary


  Plates move apart from one another, magma from the mantle rises up to make new crust, movement of plates over the mantle can cause earthquakes, rising basalt magma can create shield volcanoes, Mid Atlantic Ridge is an example
• Convergent boundary - Collision zones


  Where 2 continents collide
• Convergent boundary – Oceanic meets Continental Plate


  Oceanic plate is subducted, plate sinks into the mantle and melts to form magma, pressure of the magma builds up and escapes through weaknesses in the rock and rises up through a composite / strato volcano, volcanic eruptions are often violent, with lots of steam, gas and ash and thick andesitic lava, sinking oceanic plate can 'stick' to the continental plate and when the plates finally snap, the energy released causes violent earthquakes, the shallower the epicentre the greater the energy
• Conservative boundary


  As plates slide past each other, friction causes earthquakes, these are rare but destructive as they occur close to the surface, the San Andreas Fault is an example