CHAPTER 4 EARTHQUAKE HAZARDS

• Earthquake


  Feeble shaking to violent trembling of the Earth's surface caused by sudden movement of rocks or fault
• Earthquake detection


  • Seismic waves radiate from the earthquake focus and are detected by seismometers
• Earthquakes are caused by plate tectonics and mantle convection
• How earthquake vibrations are generated

  1. Sudden movement of rocks or fault

  2. Seismic waves radiate from earthquake focus

  3. Waves detected by seismometers
• 1. waves (Primary waves)


  Fastest seismic waves that travel through the Earth's interior
• 1. waves (Secondary waves)


  Slower seismic waves that travel through the Earth's interior
• Surface waves


  Slowest seismic waves that travel along the Earth's surface
• Seismograms record the arrival of different seismic wave types over time
• Scientists used seismic waves to determine the internal structure of the Earth
• Ground rupture


  • Displacement on the ground due to movement of a fault
• Liquefaction


  • Process that transforms sediments from solid to liquid during intense shaking
• Earthquake-induced landslide


  • Movement of rock, earth or debris down a sloped section of land caused by extreme ground shaking
• Tsunami


  A series of waves in a water body caused by the displacement of a large volume of water
• How a tsunami occurs


  1. Earthquake rocks the ocean floor

  2. Displaces volume of water, pushing it up

  3. Sets off an oscillation that develops into waves

  4. Water is sucked back from the shore

  5. Waves get bigger as water gets shallower
• TSUNAMI A.K.A SEISMIC SEA WAVE, IS A SERIES OF WAVES IN A WATER BODY CAUSED BY THE DISPLACEMENT OF A LARGE VOLUME OF WATER
• Volcanic eruptions can also trigger tsunamis when they occur underwater.
• LIQUEFACTION PROCESS THAT TRANSFORMS THE BEHAVIOR OF A BODY OF SEDIMENTS FROM A SOLID TO A LIQUID WHEN SUBJECTED TO EXTREMELY INTENSE SHAKING.
• Tectonic Earthquake

  Generated by the sudden displacement along faults in the solid and rigid layer of the earth
• Volcanic Earthquake

  Earthquakes induced by rising lava or magma beneath active volcanoes