Earthquake and Volcano

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Chapter 9 : Earthquake and Volcano

Earthquake arrow_upward

  • It is the shaking of earth due to movements of rocks along a fault.
  • An earthquake is caused by the release of energy built up in the earth.
  • When this energy is released it travels out in all directions (including up and down).
  • These earthquake waves cause the ground to shake and shatter causing plenty of damage.
  • The study of earthquake and the waves they create is called seismology.

  • Types of Earthquake and its Causes arrow_upward

  • The surface of the earth is made up of great tectonic plates of rock.
  • These plates move slowly towards, or away from, each other.
  • Sometimes when they push together they slip and there is a jolt, and that is what we feel as an earthquake.
  • There are basically two types:
    • Volcanic
    • Tectonic


  • Some earthquakes are related to volcanoes, earthquakes are along the edges of tectonic plates. This is where most volcanoes too occur.

  • Tectonic

  • The release of pressure caused by the grinding together of the tectonic plates creates the earthquake.

  • Earth Plates arrow_upward

  • The plates are made of rock and drift all over the globe; they move both horizontally (sideways) and vertically (up and down).
  • Over long periods of time, the plates also change in size.

  • Plate Tectonics arrow_upward

  • The Earth's surface is covered by a series of crustal plates.
  • The ocean floors are continually moving, spreading from the center, sinking at the edges, and being regenerated.
  • This theory explains the movement of the Earth's plates and also explains the cause of earthquakes, volcanoes and many other geologic phenomenon’s.
  • The top layer of the Earth's surface is called the Continental crust.
  • The thin crust under the oceans is called Oceanic crust.
  • Oceanic crust is thinner and denser than continental crust.
  • Crust is constantly being created and destroyed.
  • Oceanic crust is more active than continental crust.

  • Volcano arrow_upward

  • A volcano is an opening, or rupture, in a planet's surface or crust.
  • It allows hot magma, volcanic ash and gases to escape from below the surface.
  • Volcanoes can also form where there is stretching and thinning of the Earth's crust in the interiors of plates.
  • Material which erupts during volcanic eruption is lava.
  • Lava: It is a molten rock erupted from volcano, also, such rock that has cooled and hardened.
  • The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases.

  • Causes of Volcano arrow_upward

  • When the part of earth’s upper or lower crust melts, magma forms.
  • A volcano is essentially an opening through which this magma and the dissolved gases are discharged.
  • Volcanoes erupt when rock releases pressure.
  • It spreads and creates magma.
  • There are plates that are always shifting around in the ground.
  • They move 1cm every day. When the plates collide, they make a big BOOM which causes the things in the volcano to heat up.
  • Then the heat pushes everything to the opening in the volcano which causes it to erupt and shoot out.
  • Volcanoes are formed when the hot lava (magma) shoots out of the earth's crust.
  • The lava becomes hard on cooling down to form a volcanic mountain.

  • Safety for Earthquake and Volcanoes arrow_upward

    Safety for earthquake

  • Drop down; take cover under a desk or table and hold on.
  • Stay indoors until the shaking stops and you're sure it's safe to exit.
  • Stay away from bookcases or furniture that can fall on you.
  • Stay away from windows. In a high-rise building, expect the fire alarms and sprinklers to go off during a quake.
  • If you are in bed, hold on and stay there, protecting your head with a pillow.
  • If you are outdoors, find a clear spot away from buildings, trees, and power lines. Drop to the ground.

  • Safety for volcano

  • Cover your mouth and nose. Volcanic ash can irritate your respiratory system.
  • Wear goggles to protect your eyes.
  • Keep skin covered to avoid irritation from contact with ash.
  • Ash fall is very heavy and can cause buildings to collapse. Exercise great caution when working on a roof
  • Wear long-sleeved shirts and long pants.
  • Use a dust mask or hold a damp cloth over your face to help breathing

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