Geo

• Plate tectonics


  The process where convection currents in the mantle move the earth's plates, causing them to separate (diverge), collide (converge), and slide past each other (transform) at plate boundaries
• Plate boundaries


  • Divergent
  • Convergent
  • Transform
• The deepest, most powerful earthquakes occur at convergent plate boundaries, where two plates collide
• Earthquakes at convergent plate boundaries

  1. Massive friction is caused between layers of rock at subduction zones

  2. The heavier, denser oceanic plate sinks into the mantle

  3. The rough edges of rocks at either side of the boundary lock in position

  4. Stress builds up as convection currents continue to push both plates towards each other

  5. Earthquakes are generated when the rocks eventually break, allowing the plates to move forward very suddenly
• Earthquakes are also common at convergent plate boundaries where two continental plates collide and the rocks at the plate boundary lock in position
• Earthquakes also occur along fractures that appear at divergent plate boundaries as two plates separate from one another
• Many earthquakes occur along the Mid-Atlantic Ridge, but their movements often go unnoticed as no lives are lost and no property is damaged
• Earthquakes at transform plate boundaries

  1. Rocks at the edge of two plates lock in position when they attempt to slide past one another

  2. Stress builds at the boundary as convection currents try to push the plates apart
• Earthquakes produced at transform plate boundaries tend to be powerful, as the focus tends to be close to the earth's surface
• How is earthquake measured?

  Richter scale
• Where do most earthquakes occur?

  Mid Atlantic ridge
• Powerful earthquakes have been recorded at the San Andreas fault, where the Pacific plate slides past North American plate. Earthquakes tend to be powerful as the focus tends to be close to the earth's crust.
• 2011 Japan incident

  The Pacific plate (oceanic) converged with and subducted under the Eurasian plate (continental). This led to an earthquake off the coast of Japan, which caused a tsunami.
• April 2015 Nepal


  An earthquake occured which was measured by the Richter scale measuring 7.8 in Nepal. The Indian plate slipped (subducted) under the Eurasian plate, releasing a large build up of energy which caused an earthquake.
• Convergent?

  When two plates come together and the heavier, denser (oceanic) plate is subducted
• Divergent?

  when two tectonic plates move away from each other
• Transform?

  Two plates sliding past each other