disrred

• Fault


  Weak point in the tectonic plate where the pressure inside the crust is released
• Focus


  Focal point of the quake; area inside the Earth where an earthquake starts; centered on the portion of the fault that has the greatest movement
• Epicenter


  Point at the Earth's surface directly above the focus. During an earthquake, the strongest shaking occurs at the epicenter. Sometimes, the ground surface breaks along the fault. There are also times the movement is deep underground and the surface does not break
• Magnitude


  Measures the energy being released from the origin of the earthquake; measured by an instrument called seismograph
• Richter Magnitude Scale


  Measures the quantity of seismic energy released by an earthquake
• Intensity


  Strength of the trembling made by the earthquake at a place; varies relying on where you are and is determined by the Mercalli Scale
• Active faults


  Areas along in which displacement is expected to occur. Since a shallow earthquake produces displacement across a fault, all shallow earthquakes occur on active faults. These are considered to be geologic hazards
• Inactive faults


  Areas that can be identified, but which do not have earthquakes
• Earthquake is the shaking of the ground caused by the movements of tectonic plates
• Earthquakes mostly occur along the fault line
• Earthquakes can cause great damage to properties and life loss
• Various potential earthquake hazards

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

  Vibration of the ground during an earthquake; can also trigger the other hazards such as liquefaction and landslides; caused by faulting during an earthquake which releases the energy that had been built up by the application off stress to the lithosphere
• Ground rupture


  Offset of the ground; happened when fault rupture from the focus extends to the earth's surface; structures that span a surface fault are likely to suffer great damage; avoid building across, or even near these hazards
• Liquefaction


  Happened when the sand or soil and groundwater mixed during the shaking of moderate to strong earthquake; the ground becomes very soft and acts similar to quicksand; can undermine the foundations and supports of buildings, bridges, pipelines, and rocks, causing them to sink into the ground, collapse, or dissolve
• Ground subsidence


  The sinking or settling of the ground surface; can result from the settlement of native low-density soils, or the caving in of natural or man-made underground voids; movements that occurs along faults can be horizontal or vertical or have a competent of both, as a result, a large area of land can subside drastically during an earthquake
• Tsunami


  Series of giant sea waves generated by an earthquake with a magnitude of > 7.0
• Landslide


  Movement of rock, debris, or earth down a slope; plate tectonics move the soil that covers them moves with it, when an earthquake occur on areas with steep slopes, many times the soil slips causing landslides
• Tsunami is a series of giant sea waves generated by any strong earthquakes and massive volcanic eruptions
• Tsunami can cause flooding which can extend inland by a thousand ft or more
• The deadliest tsunami was the Indian Ocean (Sumatra, Indonesia) in 2004 with 350,000 casualties
• Recognizing signs of an impending tsunami

  • Feel (earthquake with magnitude > 7.0, severe shaking of the ground)
  • See (unusual sea-level fluctuations, rapid fall in sea water level, sudden rise in sea waster level, disappearance or lowering of sea water level, wall of water)
  • Hear (loud roaring sound coming from the ocean)
• Ground shaking


  Can cause objects in a building to fall which may injure anyone nearby; when the severity of the ground shaking increases, it can cause damage to the structures, or even can cause collapsing in the worst-case scenarios; can trigger liquefaction or landslides; the intensity of ground shaking depends on bedrock type, duration and intensify of the earthquake, and the distance of the area from the epicenter
• Ground rupture


  Structures built across a fault will be seriously damaged, rip apart, or collapse; structures build adjacent to the fault will acquire less damage compared to the structures built across
• Liquefaction


  When a ground acts as a quicksand, the foundation and support of structures to sink into the ground, overturn, or collapse; underground pipes and tanks may rise to the surface, after the event, areas can be left covered in a deep layer of mud
• Ground subsidence


  When the ground surface subsides totally, the void left may stock water causing a permanent flood in the area (ground subsides due to ground shaking or downward displacement of one side of a fault during an earthquake)
• Tsunami


  Can destroy houses, uproot trees, devastate nearby properties, and drown and kill people and animals
• Flood


  Can also be caused by overflowing of water from dams, reservoirs or river (earthquake can break dams and ripraps of rivers causing the water to overflow and flood the area)
• Landslide


  During earthquakes, rocks and soil rapidly roll along steep sloped; the falling rocks may hit people, houses or vehicles causing accidents
• Fire


  Earthquake can overturn electrical posts, break power lines and gas lines which usually starts fire causing great loss in properties and lives
• Earthquake hazard map is a special type of map that shows the possible physical and geographical effect of an earthquake within a particular area or region
• Experts can create earthquake hazard map by analyzing the geographical features and historical seismic record of a particular region; they can locate fault lines or tectonic plate boundaries to determine which areas are at risk of earthquakes
• Experts can also create an earthquake hazard map that shows susceptibility of a region to ground shaking; 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. Each kind of ground material composition reacts to seismic waves differently. Experts can analyze geographical maps that contain info about the distribution of different rock units, soil compositions, and ground conditions to create an earthquake hazard map
• We cannot accurately predict the location, time, and magnitude of an earthquake. However, by evaluating various geographical map info, we can create a ground shaking susceptibility map that can tell us the most at risk areas even without knowing where and when an earthquake will appear. Such map is important land use management, building codes formulation, and risk assessment
• Volcanic eruption is the release of molten rocks and gas from the mantle of the earth to the above surface; cannot be accurately predicted
• Volcano-related hazards


  • Lava flow
  • Pyroclastic density current
  • Tephra falls
  • Volcanic gas
  • Lahar
  • Tsunami
• Lava flow


  Molten volcanic rock flowing out of the erupting crater or fissure; can bury, crush, cover and burn anything in its path; least dangerous; speed: 3 km/day to 50km/h (determined by the lava's viscosity, density, local area's land features)
• Pyroclastic density current


  Moving masses of mixed volcanic rock fragments and hot gasses; produced when an eruption column collapse; fast moving mixture of fragmented volcanic materials and hot gasses; dangerous phenomenon
• Pyroclastic flow


  High concentration, move in contact with ground, confine to valleys