DRRR

• An event like a volcanic eruption remains a natural event if it does not pose a threat to defined elements at risk
• A hazard will be declared if it poses a threat with respect to elements at risk because it is along the potential path or within affected areas
• A disaster happens when the probable destructive agent hits a vulnerable populated area
• The number of people or structures within the area exposed to hazards is the most reliable and least subjective indicator of exposure
• A man-made hazard is a hazard originating from technological or industrial conditions, including accidents, dangerous procedures or infrastructure failures
• Vulnerability refers to the severity of loss or damage due to the occurrence of a hazard
• Intensity is a measure on the impacts on the ground, on people, and on structures
• Frequency refers to how often an event occurs
• A biological hazard refers to a biological substance that poses a threat to the health of living organisms, primarily humans. These hazards can arise from various sources such as microorganisms (bacteria, viruses, fungi), toxins produced by living organisms (venoms, toxins from certain plants or animals), or biological materials derived from living organisms (pollen, mold spores)
• Strike-slip fault is associated with horizontal movement along the fault plane
• Topple is a type of landslide which occurs suddenly when a massive part of very steep slopes breaks loose and rotate forward
• Correct sequence of development stages for a tropical cyclone, moving from the least intense to the most intense

  1. Tropical Depression

  2. Storm

  3. Typhoon
• Tornadoes are narrow, funnel or cylindrical-shaped, and intensely-rotating columns of wind that form during powerful thunderstorms and extend from the base of a cumulonimbus cloud down to the earth's surface
• Liquefaction is a geological phenomenon that occurs when saturated soil loses its strength and stiffness due to an applied stress, such as shaking during an earthquake
• Tsunamis are a series of large ocean waves generated by sudden movements of the Earth's crust beneath the ocean floor, such as earthquakes, volcanic eruptions, underwater landslides, or meteorite impacts
• The elastic rebound theory is a geological concept that explains the occurrence of earthquakes along fault lines. The theory suggests that before an earthquake, stress accumulates along a fault line as tectonic plates slowly move past each other. This stress causes the rocks on either side of the fault to deform elastically, storing potential energy like a stretched rubber band
• The growth stage of a fire is the shortest of the four stages. It takes place when the heat release rate increases as result of the burning of additional fuel
• The fire tetrahedron is a visual aid that reminds us of the four important ingredients required to initiate and sustain fire: Oxidizing Agent, Heat, Uninhibited Chemical Reaction, and Fuel
• Class B refers to a type of fire that can be extinguished by forming a blockade between oxygen and the fuel, for instance, by applying a layer of foam
• The most abundant volcanic gas released into the atmosphere is water vapor
• Ballistic projectiles are a special kind of tephra
• A third-degree burn is a type of burn which is referred to as a full-thickness burn and skin is gray, dry and with no feeling sensation
• Bolide


  Any extraterrestrial Object
• What happens when an asteroid, a comet, or a meteoroid hits the Earth's surface

  1. The portion of the ground that is hit becomes severely compressed and deformed

  2. Rock fragments from the impact site (called ejecta) hurl into the atmosphere and eventually fall back to the ground around a bowl-shaped depression surrounded by a raised rim

  3. The depression excavated by the impactor is called an impact crater
• Projectile from space

  • Asteroids
  • Comets
  • Meteoroids
• Bolide impacts happen almost anywhere and they have happened a lot more than what we might think!
• Meteorite impact craters on Earth may not be that abundant because of weathering, erosion, volcanism, and tectonic activity
• The only impact craters on Earth that can still be seen are the younger ones, the larger ones, or those which hit areas which are tectonically stable and are not subject to modification by active surface processes
• Evidence of Past Impacts


  • Impact Crater
  • Meteorite/s
  • Materials like tektites, impact breccia, shatter cones, impact spherules, shocked quartz
  • Chemical traces such as anomalously high levels of iridium
  • Geophysical signatures like circular magnetic and gravity (density) anomalies and seismic reflection images
• Very strong earthquakes reaching up to magnitude 13 in the Richter scale and, subsequently, aftershocks of gradually decreasing magnitude
• Drastic changes in climatic conditions
• Acid rain
• Ground subsidence


  The relative lowering of the earth's surface usually with respect to the mean sea level
• Causes of ground subsidence


  • Carbonate dissolution and collapse
  • Excessive groundwater withdrawal
  • Extraction of oil and natural gas
  • Earthquakes
  • Underground mining methods
  • Isostatic rebound
  • Change in season
• Effects of ground subsidence


  • Sudden ground collapse events can be catastrophic but are usually isolated and very limited in the expanse
  • Slow subsidence can proceed almost unnoticeably but may still cause serious, widespread damage to property
• Mitigating subsidence-related hazards


  1. Map out the areas which are subsidence-prone and to either avoid development in the area or adapt by modifying or strengthening structures

  2. Areas which experience subsidence are prone to severe, extensive, and prolonged flooding so structures and roads, for instance, could be elevated, and dikes and pumping or drainage systems can be constructed
• Coastal erosion


  A natural process which shapes shorelines by the wearing away of coastal land or beaches, mainly by the impact of waves along the shoreline. Sand particles and rock fragments carried by the high-energy waves crashing into headlands accelerate the process
• Natural causes of coastal erosion


  • Waves
  • Currents
  • Tides
  • Wind-driven water
  • Ice
  • Rainwater
  • Groundwater
  • Wind
• Man-made causes of coastal erosion


  • Removal of vegetation cover exposing sediment to wind and water action
  • Concentration of drainage water flow into the sea causing erosion of that part of the coast
  • Construction of structures including coastal erosion control structures that interfere with the natural flow of coastal materials, causing erosion in adjacent areas of the shore
  • Building activities that damage natural protective features
  • Activities which destroy natural protective features such as dunes and vegetation cover
  • Shipping and boating activities producing extra wave action
• Managing coastal erosion

  1. Preservation of and restriction of activities and development in natural protective features (e.g., dunes and beaches)

  2. Regulating coastal erosion protection structures to ensure that natural protective features are not damaged

  3. Prohibiting construction in areas of active coastal erosion and in areas within reach of coastal storms

  4. Restricting development of public utilities in areas prone to coastal erosion to discourage new development in these areas