earthquakes

• PH will always be associated with earthquakes because of its position near the pacific ring of fire.
• 7.1 - the expected magnitude of the big one earthquake
• 100x stronger: magnitude 7.1 to 9.1
• magnitude - size of an earthquake or energy released
• richter scale and moment magnitude scale - used to measure magnitude
• moment magnitude scale - more precised way to measure magnitude
• intensity - amount of damage
• mercalli scale - used to measure intensity of an earthquake
• 1 to 12 - range in mercalli scale
• 1 to 10 - range in richter scale
• focus - earthquake's point of origin
• epicenter - point directly above the focus of an earthquake
• earthquake - caused by sudden movement of the earth's crust due to a release of pressure along a fault line
• causes of earthquake occurrence:

  1. plates get stuck (due to friction since they are always moving)
  2. plates that get stuck cause strain on the ground
  3. amount of stress along the fault exceeds strength of the fault since stress overcomes friction
  4. this stress causes sudden release of stored elastic energy; hence the shake
• what type of fault is this?

  normal dip-slip

  
• what type of fault is this?

  reverse dip-slip or thrust fault

  
• what type of fault is this?

  strike-slip

  
• 2 classifications of earthquakes based on medium they travel in:

  1. Body Waves
  2. Surface Waves
• 2 types of surface waves:

  1. rayleigh waves
  2. love waves
• P waves - type of body wave that push (compress) and pull (expand) rocks in the direction they are travelling
• P waves - can travel through solid, liquid, and gas
• P waves - the fastest seismic wave
• S waves - type of a body wave that shake particles at right angles to the direction of travel
• S waves - cannot travel through liquids or gases
• Surface Waves - trapped near earth's surface ---do not travel through the body like P waves and S waves
• Rayleigh Waves - more similar to water particles in ocean waves; movement: forward and down then backward and up (elliptical motion)
• Love Waves - causes more damage since they are perpendicular to the direction where wave travels
• Surface Waves - predominantly lower frequency than body waves
• Surface Waves -  easily distinguished on a seismogram
• Body Waves - they originate at the epicentre of the earthquake and travel through the earth at amazing speeds.
• Surface waves - waves that travel on the surface of the earth
• Surface Waves - destruction caused by earthquakes is primarily done by these waves
• S waves - second waves to hit the seismographs
• P waves - first waves to hit the seismographs when an earthquake strikes
• wave propagation - movement of waves
• epicenter - in what part of the earthquake is intensity the greatest?