Earthquakes

Earthquakes are caused by the release of built-up pressure inside the Earth's crust. An earthquake's power is measured on the Richter scaleusing an instrument called a 'seismometer'.An earthquake is the shaking and vibration of the Earth's crust due to movement of the Earth's plates (plate tectonics). Earthquakes can happen along any type of plate boundary

• short-term (immediate) impacts
• long-term impacts
• social impacts (the impact on people)
• economic impacts (the impact on the wealth of an area)
• environmental impacts (the impact on the landscape)

MEDC= A more economically developed country

LEDC= A less economically developed country

Different plate boundaries

• At a tensional, constructive or divergent boundary the plates move apart.
• At a compressional, destructive or convergent boundary the plates move towards each other.
• At a conservative or transform boundary the plates slide past each other.

  Key facts

  • A volcano is formed by eruptions of lava and ash.
  • Volcanoes are usually cone shaped mountains or hills.
  • When magma reaches the Earth's surface it is called lava. When the lava cools, it forms rock.
  • Volcanic eruptions can happen at destructive and constructive boundaries, but not at conservative boundaries.
  • Some volcanoes happen underwater, along the seabed or ocean floor.

• Shield volcanoes are usually found at constructive or tensional boundaries.
• They are low, with gently sloping sides.
• They are formed by eruptions of thin, runny lava.
• Eruptions tend to be frequent but relatively gentle.