The Restless Earth

1. Plates move towards each other.
2. Oceanic crust forces underneath continental crust.
   1. This is called 'subduction' and it occurs are a 'subduction zone.'
3. Oceanic melts into the mantle.
4. As the crusts rub against each other they cause friction.
5. Rock is destroyed.
6. Collision Zone
   1. Two continental plates collide.
      1. Neither is forced under so they're forced uupwards.

1. Plates move away from each other.
2. Happens between two pieces of continental crust.
3. As they move apart due to the convection currents in the mantle, the gap is filled by magma.
   1. Magma then cools and solidifies.
4. Can lead to the creation of ocean ridges.

1. Plates slide past each other.
   1. - At different speeds in the same direction.
      1. or - In opposite directions.
2. Plates often get stuck, building up pressure that often causes powerful earthquakes.
3. No rock is created or destroyed.

1. Occur at collision boundaries
2. See notes page for formation and uses.

   Attachments:

   • Fold Mountains

1. Occur at destructive boundary at the subduction zone.
2. Often near fold mountains.
3. Widely found in the Pacific Ocean.

1. Capacity to erupt x100 more material than normal volcano.
2. Flat and wide.
   1. Often found under the ocean.
3. Has a caldera instead of a crater.
   1. Depression in the top.

1. Composite
   1. Alternating layers of lava and ash.
   2. Usually found at destructive boundaries.
   3. May erupt pyroclastic flow instead of regular lava flow.
   4. Tall and steep.
   5. Formed by thick, viscous lava.
2. Shield
   1. Low, gentle sloping.
   2. Usually found at constructive boundaries.
   3. Frequent but gentle eruptions.
   4. Formed by thin, runny lava.
3. Vents
   1. Main - main place for magma to escape.
   2. Secondary - this vent opens in the first becomes blocked.
4. Can be:
   1. Dormant - temporarily inactive
   2. Extinct - Never likely to erupt again.
   3. Active - erupts frequently.

1. Uses information collected by seismometers which collect information on the amount of movement and the strength of the shock waves.
2. 0 - Infinity
   1. No upper limit.
3. 10 fold. Each number on the scale is x10 more powerful than the previous.
   1. eg. 2 is x10 more powerful than 1.

1. Measures earthquake by damage.
2. 1-12 / I-XII
   1. 1 - barely felt. 12 - total destruction.
3. Can be represented as pictures/diagrams.

Attachments:

• Effects of Natural Disaster

1. Aftershocks can cause more damage.

1. The entire depth of the sea is set in motion by an event, displacing the water above it and creating a wave.
2. One plate is dragged under another, stress on the boundary causes the edges to flex and deform.
   1. The plates flex back into their original place, displacing all the water above.

1. 5-10km thick.
2. More dense.

1. 25-100km thick.
2. Less dense.