G10-Q1-SCIENCE-01

• What are earthquakes?

  Earthquakes are the vibrations of Earth due to a sudden and rapid release of energy.
• What causes the shaking of the ground during an earthquake?

  The shaking of the ground is due to rapid and sudden movement of the Earth's crust.
• Which part of the Philippines has no record of earthquakes?

  Palawan has no record of earthquakes.
• Why does Palawan have no record of earthquakes?

  Palawan is not technically part of the Philippines and only drifted nearby from another country.
• What is a fault in the context of earthquakes?

  • A fracture in the rocks that make up the earth’s crust.
  • Formed due to internal stress.
  • Locked due to confining pressure.
  • Not to be confused with joints, which have no displacement.
• What is the epicenter of an earthquake?

  The epicenter is the point on the surface of the Earth directly above the focus.
• What does the term "focus" or "hypocenter" refer to in an earthquake?

  The focus is the point within the earth where an earthquake rupture starts.
• What are seismic waves?

  Seismic waves are waves that transmit the energy released by an earthquake.
• What are the destructive natural forces caused by earthquakes?

  • Shaking of ground
  • Liquefaction of soil
  • Destruction
  • Fires
• Who proposed the elastic rebound theory?

  Harry Fielding Reid proposed the elastic rebound theory.
• What did Harry Fielding Reid analyze to propose the elastic rebound theory?

  He analyzed the effects of the 1906 San Francisco Earthquake.
• What does the elastic rebound theory describe?

  The elastic rebound theory describes how the crust or rocks behave elastically, accumulating and releasing stress and strain.
• What are the steps involved in the elastic rebound process?

  1. The crust is in its original position.
  2. Strain and elastic energy build up; frictional resistance resists differential stress.
  3. Differential stress overcomes frictional resistance, causing slippage and releasing energy.
  4. The earthquake stops, and the plates return to their original position, but landmarks are displaced.
• What are the two categories of mechanical waves?

  • Longitudinal Waves: cause vibrations parallel to the direction of the wave.
  • Transverse Waves: cause vibrations perpendicular to the direction of the wave.
• What are body waves in the context of seismic waves?

  Body waves are waves that move through the Earth.
• What are P Waves and their characteristics?

  P Waves are the fastest type of seismic wave and can move through solid, liquid, and gas phases of matter.
• What are S Waves and their characteristics?

  S Waves are detected after P Waves and can only move through solids, moving in an up and down motion.
• What are surface waves and their characteristics?

  • Surface waves move only through the surface.
  • They are generally slower than body waves.
  • They are easily distinguishable in a seismogram.
• Who discovered Love Waves?

  Augustus Edward Hough Love discovered Love Waves in 1911.
• What are Rayleigh Waves and their characteristics?

  Rayleigh Waves move in a rolling motion, similar to ocean waves, and are the slowest seismic waves.
• What are seismographs used for?

  Seismographs are tools used to record the vibrations of an earthquake.
• How do seismographs record earthquake vibrations?

  Seismographs record vibrations on a sheet called a seismograph.
• In what order do seismic waves arrive during an earthquake?

  P waves arrive first, followed by S waves, and then surface waves.
• What does the amplitude on a seismograph indicate?

  The amplitude indicates the intensity that the ground shakes or vibrates during the earthquake.
• What is seismology?

  • Seismology is the study of earthquakes and related phenomena.
  • It involves studying seismic waves and their effects.
• What is the purpose of a seismometer or seismograph?

  It is used to record an earthquake’s characteristics.
• How is the duration and amplitude of an earthquake recorded?

  The duration and amplitude are recorded on a seismogram.
• What does the Modified Mercalli Scale measure?

  The Modified Mercalli Scale measures the degree of shaking based on observed effects.
• Who was the Modified Mercalli Scale named after?

  It was named after Giuseppe Mercalli in 1883.
• How many levels of severity does the Modified Mercalli Scale have now?

  The Modified Mercalli Scale now has 12 levels of severity based on observed effects.
• What is magnitude in the context of earthquakes?

  Magnitude is the scientific and objective way of measuring the shaking of an earthquake.
• Who developed the Richter Scale?

  Charles Richter developed the Richter Scale in 1935.
• What does the Richter Scale quantify?

  The Richter Scale quantifies the actual ground motion of an earthquake.
• How does the Richter Scale increase in magnitude?

  The scale has a 10-fold wave amplitude increase, meaning each magnitude is 10 times greater in strength than the last.
• What are the steps in finding the Richter Magnitude?

  1. Find the time interval or distance to the epicenter.
  2. Measure the height of the largest amplitude.
  3. Plot the time interval and amplitude to find the Richter Magnitude.
• What is moment magnitude?

  Moment magnitude is the measure of magnitude based on the seismic moment, ideal for larger earthquakes.
• What is triangulation in the context of earthquakes?

  Triangulation is the method used to approximate the epicenter of an earthquake using three nearby seismograms.
• What are the four factors that contribute to the destruction caused by seismic vibrations?

  • Intensity
  • Duration of shaking
  • Nature of building materials and construction practices
  • Nature of material upon which structures rest
• What is liquefaction in the context of earthquakes?

  Liquefaction occurs when loose or saturated soil behaves like a mobile fluid during an earthquake.
• How can earthquakes cause fires?

  Earthquakes may cause fires by damaging gas stations or igniting flammable materials in buildings.