LESSON 6

• Fault


  zone of fractures between two blocks due to ground movement
• Epicenter


  is the point on the Earth's surface directly above the focus
• Focus


  also knows as hypocenter; it is the origin of the earthquake
• Fault Line Subsurface


  a fault below the ground
• Earthquake Hazards


  refers to earthquake agents which have the potential to cause harm to a vulnerable targets which can either be humans, animals, or even your environment
• Primary Effects


  are permanent features an earthquake can bring out
• Primary Effects


  Fault Scraps, Surface Ruptures, and Offset of natural or human-constructed objects.
• Secondary Effects


  happen when ground movement results to other types of destruction
• Secondary Effects


  Landslides, tsunamis, liquefaction, and fire
• Landslides


  Can have particularly devastating effects like floods, blocking of rivers, death, and damage to land and natural resources
• Tsunami


  a huge sea wave triggered by a violent displacement of the ocean floor
• Tsunami


  Underwater earthquakes, volcanic eruptions, or land slides can cause _____
• Liquefaction 


  Earthquake motion can turn loosely packed, water-

  saturated soil to liquid
• Liquefied soil becomes less compact and ultimately

  lose the ability to support roads, buried pipes, and, of

  course, houses. It is caused by vibration or saturation

  with water which causes the soil to decrease in density.

  This poses danger for it lead to unstable structures of

  buildings due to ground subsidence.
• Fires


  Even moderate ground

  shaking can break gas and electrical lines, sever

  fuel lines, and overturn stoves. To further

  complicate things, water pipes rupture, so it

  would be impossible to extinguish the fire.
• Effective recording and interpretation of ground motion.

  This can be done by effective instrumentation in order to

  determine the location, strength and frequency of

  earthquakes. This assists in providing alerts and warnings

  especially to high-risk or vulnerable areas for preparation

  and emergency response.
• Constructing seismic hazard maps


  A seismic hazard map shows the potential hazards in a

  given area. In many regions in our country, seismic

  expectancy maps or hazard maps are now available for

  planning purposes. It serves as basis for disaster

  management information like locations for evacuation and

  evacuation routes. The anticipated intensity of ground

  shaking is represented by a number called the peak

  acceleration or the peak velocity.
• Developing resistant structures


  Resistant structures are able to withstand collapse by

  redistributing forces caused by seismic waves through

  shear walls. Developing engineered structural designs

  that are able to resist the forces generated by seismic

  waves can be achieved either by following building

  codes based on hazard maps or by appropriate methods

  of analysis.
• Most Commonly used Methods of Reducing Earthquake Risks

  • Effective recording and interpretation of ground motion
  • Constructing seismic hazard maps
  • Developing resistant structures
• Signs of an Impending Tsunami

  • Feel an earthquake
  • See ocean water disappear form beach, bay, river
  • Hear an unusual roaring sound