Earthquake!

• Earth


  Consists of different layers
• Crust


  • First layer of the Earth
  • Made up of several large and small plates
• Mantle


  • Middle layer of the Earth
  • Widest layer of the Earth
  • Mostly made up of magma
• Upper Mantle


  • Part of the mantle closer to the crust
• Lower Mantle


  • Part of the mantle below the upper mantle
• Core

  • Central layer of the Earth
  • Divided into outer core (liquid layer) and inner core (solid layer)
• Earth's layers


  Can be compared to a hard-boiled egg
• The Earth's crust is broken into plates, like broken pieces of eggshell
• Movement of plates on the Earth's crust

  Often accompanied by earthquakes or volcanic eruptions
• Earthquake

  Shaking of the ground
• Cause of earthquakes

  1. Crustal plates move and push towards each other or away from each other

  2. Nearby rocks break and slide past each other

  3. Waves of energy are released and sent out through the Earth
• Seismograph


  Instrument that measures the motion of the ground during an earthquake
• Types of earthquakes

  • Volcanic earthquakes
  • Tectonic earthquakes
• Volcanic earthquake

  Shaking of the ground due to a strong volcanic eruption
• Tectonic earthquake


  Caused by the movement of the Earth's crust or crustal plates
• Magnitude


  Refers to the amount of energy released by an earthquake from its focus
• Intensity


  Refers to the effect of an earthquake, especially the damages
• Magnitude is written in numbers with decimals, while intensity is written by Roman numerals
• Focus


  The break in the ground caused by the pressure of the moving rocks, where the earthquake originates
• Epicenter


  The ground above the focus
• Richter scale


  Used to measure the magnitude of an earthquake
• The Philippine Institute of Volcanology and Seismology (PHIVOLCS) is the government agency responsible for monitoring earthquakes in the Philippines
• Earthquake magnitude and effects

  • 0 to 1.9: Only detectable by seismograph
  • 2 to 2.9: People may feel it and observe hanging objects swinging
  • 3 to 3.9: Ground movement comparable to vibration of a passing truck
  • 4 to 4.9: May break windows and cause small or unstable objects to fall
  • 5 to 5.9: May damage a well-built structure and severely damage a poorly built structure
  • 6 to 6.9: May cause cracks on concrete walls and chunks of plaster and concrete to fall
  • 7 to 7.9: May cause buildings to displace from foundations, cracks on Earth's surface, and some underground pipes to break
  • 8 to 8.9: May destroy bridges and leave only a few structures standing
  • 9 and above: Near total destruction
• Intensity


  Refers to the effects of the earthquake, such as destruction of buildings, infrastructure, crops, and casualties
• The Philippines is frequently hit by earthquakes due to its location in the circum-Pacific belt, also known as the Pacific Ring of Fire
• Earthquakes can cause a lot of damage:

  • Buildings, roads, bridges and other structures can break.
  • Landslides can happen in mountains, burying houses and roads.
  • Fires can start from broken electrical wires or overturned stoves.
  • Floods can happen if dams break or rivers get blocked by rocks.
  • The ground itself can crack and move.
  • Giant waves called tsunamis can happen in the ocean.
  • In some places, the ground can turn to liquid during an earthquake.
  • Sadly, many people can be hurt or killed by earthquakes.