Natural hazards

• a natural hazard is a threat to people or property
• Geological hazards are caused by land and tectonic processes
• meteorological hazards are caused by weather and climate
• primary effects of a natural hazard are the immediate impacts caused by the hazard itself.
• examples of primary effects:

  • buildings and roads destroyed
  • ppl injured or killed
• examples of secondary effects:

  • initial hazard can trigger other hazards
  • shortage of clean water makes it easy for diseases to spread
• destructive margins are when two plates are moving towards each other ( oceanic and continental) and the oceanic crust is pushed underneath because it is denser.
• volcanoes and ocean trenches are formed from destructive plate margins
• constructive plate margins are where two plates are moving away from each other. magma rises up to fill the gap and cools, creating new crust
• conservative margins are where two plates are moving sideways past each other.
• at destructive plate margins, the oceanic plate moves down into the mantle where it melts and forms magma. The magma rises through vents forming volcanes
• at constructive plate margins the magma rises into the gap created by the plates moving apart, forming a volcano
• earthquakes are formed by tension that builds up at all three types of plate margins
• destructive margins- tension builds when one plate gets stuck as it moves past the other.
• constructive plate margins- tension builds along cracks in the plates as they move away from each other
• conservative plate margins- tension builds up when plates that are grinding past each other get stuck
• earthquakes- plates move past each other, sending out shock waves. the shock waves spread out from the focus. the waves are stronger near the focus and cause more damage.
• the epicentre is the point on the earths surface directly above the focus
• global atmospheric circulation is the transfer of heat from the equator to the poles by the movement of air
• earthquakes are measured using the moment magnitudes scale
• the moment magnitudes scale measures the amount of energy released by an earthquake
• ash from volcanoes makes the ground really fertile and can be used to grow crops
• volcanoes are tourist attractions so ppl can get work
• the middle cell is called the ferrel cell and it goes the other way to the others and acts like a gear
• the cell nearest the equator is called the Hadley cell
• the cell nearest the poles is called the polar cell
• the centre of a storm is called the eye
• the eye is surrounded by the eye wall, where theirs very strong winds