Earthquakes

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Some definitions

Focus: The point underground where a quake occurs. The closer the focus is to the surface, the bigger the impact.

Epicentre: The location directly above the focus where the damage wil be worst.

Seismic (shock) waves- Fast waves of energy released by a quake that travel through the rocks to the surface and can be picked up on a seismograph.

Richeter Scale: It is used to measure the magnitude (amount of energy released) of a quake. The scale ranges from 0-10. An increase of one means the quake is ten times as powerful as the previous number.

Aftershocks: A series of smaller tremors in the days after the quake slowing rescue efforts and causing more damage.

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Factors affecting Earthquakes and Impacts

Factors:

  • Magnitude: A stronger earthquake will do more damage.
  • Time of day: People sleep at night which may lead to more deaths.
  • Building design: Buildings with foundations deep in the ground will not fall as easily as ones on the surface.
  • Emergency service response: A better one will handle the situation better.
  • Education: People will know what to do in the event of an earthquake.

Primary Impacts:

  • People are killed by falling debris
  • Roads are damaged and impassable
  • Buildings are reduced to rubble

Secondary Impacts:

  • Lack of clean water causes diseases
  • Broken gas pipes lead to fires that destroy buildings and kill people.
  • Family members are split up.
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Prediction and Protection

Predicting:

  • Animals may act strangely.
  • Water levels may rise in lakes and wells due to cracks in the rocks.
  • A tiltmetre checks movement in the rocks
  • Foreshocks can be measured on a seismograph.

The probelm with prediction is that earthquakes happen so quickly that prediction methods can be useless.

Protection:

  • Deep foundations keep buildings firmly in place.
  • Overlapping and hollow bricks hold together better and cause less damage.
  • Automatic window shutters prevent falling glass.
  • Automatic sprinkling system and gas shut off prevent fires.
  • Cross bracing gives added strength and prevents twisting.
  • Reinforced steel pillars provide strength and flexibility.
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Haiti Earthquake

ItThis happened on 12/01/10. Hati is on a conservative margin. The Caribbean plate moved Eastwards parallel to the Gonave platelets moving Westwards. They were caught whilst sliding past each other and pressure built released as a destructive earthquake.

Strength: 7.0                    Epicentre: Port-au-Prince (Capital)

Primary Impacts: 230,000 deaths. 300,000 injured. Roads and bridges destroyed. 10 billion dollars of damage. Schools and hospitals destroyed.

Secondary impacts: Stress and trauma affect mental health. Damaged water supplies cause risk of disease. Looting and violence to get provisions. Months of sleeping on the streets. Many have no basic food or clothing.

Why were the impacts so bad?              PHYSICAL                     HUMAN

It was a strong Earthqake. It had a shallow focus so seismic waves were stronger causing more damage.

There were weak buildings with no regulations. Haiti is very poor. There were few emergency services. Medical staff were killed in the quake so there was little madical help. Roads were impassable and destroyed so the arrival of supply was delayed.

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