DISRRED FINALS

• Earthquake


  Shaking of the ground caused by the movement of tectonic plates, mostly occurs along the fault line, can cause great damage to properties and life loss
• Various Potential Earthquake Hazards

  • Ground Shaking
  • Ground Rupture
  • Liquefaction
  • Ground Subsidence
  • Tsunami
  • Landslide
• Earthquake Hazards


  • These hazards, which can lead to serious disasters, depend on the strength of seismic activity. Factors affecting it are local topographic and built features, subsurface geology, and groundwater.
• Ground Shaking


  Vibration of the ground during an earthquake, can also trigger other hazards such as liquefaction and landslides
• Ground Rupture


  Offset of the ground caused by fault rupture from the focus extending to the Earth's surface
• Liquefaction


  Sand or soil and groundwater mix during shaking causing the ground to act like quicksand, undermining foundations and supports
• Ground Subsidence


  Sinking or settling of the ground surface, can result from settlement of low density soils or caving in of underground voids
• Tsunami


  Series of giant sea waves generated by strong earthquakes and massive volcanic eruptions, can cause flooding extending inland by a thousand feet or more
• Landslide


  Movement of rock, debris or earth down a slope, caused by earthquakes on areas with steep slopes
• Earthquake Hazard Identification

  1. Ground Shaking

  2. Ground Rupture

  3. Liquefaction

  4. Ground Subsidence

  5. Tsunami

  6. Landslide
• Ground shaking can cause objects in buildings to fall and injure people, and can also trigger liquefaction and landslides
• The intensity of ground shaking depends on bedrock type, duration and intensity of the earthquake, and distance from the epicenter
• Structures built across a fault will be seriously damaged, while those adjacent to the fault will acquire less damage
• Liquefaction causes structures to sink into the ground, overturn, or collapse, and can leave areas covered in mud
• Ground subsidence can cause permanent flooding in areas where the ground surface sinks
• Tsunami can destroy houses, uproot trees, devastate nearby properties, and drown people and animals
• Earthquake can break dams and ripraps of rivers causing water to overflow and flood the area
• Falling rocks from landslides during earthquakes can hit people, houses or vehicles causing accidents
• Earthquake can overturn electrical posts, break power lines and gas lines which usually starts fire
• Earthquake Hazard Map


  Special type of map that shows the possible physical and geographical effect of an earthquake within a particular area or region, also known as a ground shaking hazard map
• Earthquake Hazard Map of Philippines

  • Region 3 has the most provinces at high risk, including Zambales, Tarlac, Pampanga and Nueva Ecija
  • National Capital Region has medium risk
  • Numerous provinces in Mindanao are at high risk, including Dinagat Islands, Surigao del Norte, Surigao del Sur, Agusan del Sur, Davao Oriental, Sarangani, and Maguindanao
• The locations of active faults throughout the Philippines align with the location of provinces at high risk of earthquakes
• Ground Shaking Hazard


  Caused by the release of stored energy in the lithosphere during an earthquake, its strength is measured in terms of velocity, acceleration, frequency and duration
• Ground shaking also depends on the properties of the ground material and the geology of the area involved, as different ground compositions react to seismic waves differently
• Earthquake Hazard Map


  • Shows the possible physical and geographical effect of an earthquake within a particular area or region
  • Can be created by analyzing the geographical features and historical seismic record of a particular region
  • Can be created by analyzing geographical maps that contain information about the distribution of different rock units, soil compositions, and ground conditions
  • Is important for land use management, building codes formulation, and risk assessment
• Potential Earthquake Hazards


  • Ground shaking
  • Ground rupture
  • Liquefaction
  • Ground subsidence
  • Tsunami
  • Landslide
• Ground shaking


  Vibration of the ground during an earthquake
• Ground rupture


  Offset of the ground
• Liquefaction


  Mixing of soil and groundwater which acts like a quicksand
• Ground subsidence


  Sinking or settling of the ground surface
• Tsunami


  Series of giant sea waves generated by an earthquake with magnitude greater than 7.0
• Volcano-related Hazards

  occurences or events directly or indirectly caused by volcanic activity potentially dangerous to life and can create damage to property
• Lava Flow (direct)

  • molten volcanic rock flowing out of the erupting crater or fissure
  • can bury, crush, cover, and burn anything in its path
• Pyroclastic Density Current (direct)

  • moving masses of mixed volcanic rock fragments and hot gasses
• Pyroclastic flow

  • high concentration, move in contact with ground, confined to valleys
• Pyroclastic surge

  • low concentration, move above ground, expand over hill and valleys
• Tephra falls (direct)

  • shower of pyroclastic materials
  • ash - less than 2mm in diameter
  • lapilli - 2-64 mm in diameter
  • blocks - >64mm
• Volcanic bombs

  • large blobs of magma that harden in the air
• Lapilli

  • little stones
  • pebble-like bits of magma that hardened before the hit the ground
• Volcanic ash

  • when the gasses in stiff magma expand rapidly and the walls of the gas bubbles explode into tiny, glass-like slivers