DRRR LESSON 6–8

• Volcanic hazards


  Observable facts arising due to volcanic activity such as eruption, with potential threat and foreseeable crisis that directly affect humans, animals, properties, infrastructure, tourism, and political stability
• Volcanic hazards

  • Ballistic projectiles
  • Ash fall
  • Pyroclastic flows
  • Lava flows
  • Volcanic gases
  • Debris Avalanche or Volcanic landslide
  • Tsunami
• Lahars


  Rapidly flowing thick mixtures of volcanic sediments (from pyroclastic materials) and water, usually triggered by intense rainfall during typhoons, monsoons, and thunderstorms. Can destroy by direct impact, block tributary streams and form a lake, and bury valleys and communities with debris.
• Ash fall or Tephra fall


  Minute volcanic particles such as pulverized rock, minerals and silicon with fine to coarse grain, formed during explosive volcanic eruption when dissolved gases in magma escape violently into the atmosphere
• Pyroclastic Flows


  Highly-density mix of hot lava blocks, pumice, ash and volcanic gases that move at very high speed down volcanic slopes, typically following valleys. Consists of a lower (basal) flow of coarse fragments and a turbulent cloud of ash above the basal flow.
• Ballistic projectiles


  Rock fragments ejected from volcano's mouth that are comparable to cannonballs, reaching up to 5 kilometers or 3 miles. Endanger life and property through impact force, loss of agricultural lands, suspensions of fine-grained particles, and carrying of noxious gases, acids, salts, and heat.
• Volcanic gases


  Magma contains dissolved gases which provide the driving force for most volcanic eruptions. As magma rises and pressure decreases, gases are released from the liquid portion of the magma and travel upward, eventually being released into the atmosphere.
• Lava flows


  Streams of molten rocks that are poured or oozed from an erupting vent. Lava flows rarely threaten human life because they move slowly, characterized as quite effusive.
• Debris Avalanche or Volcanic landslide


  Massive collapse of a volcano, usually triggered by an earthquake or volcanic eruption.
• Tsunami


  Sea waves or wave trains generated by sudden displacement of water, could be caused by undersea eruptions or debris avalanches.
• Seismic hazard


  Hazard related to probable earthquakes in a particular area, normally shown in a seismic hazard map that indicates the likelihood of disaster affecting people and how they can prepare.
• Active volcano


  A volcano that has had at least one eruption during the past 10,000 years. It might be erupting or dormant.
• Erupting volcano


  An active volcano that is currently having an eruption.
• Dormant volcano


  An active volcano that is not erupting, but is expected to erupt again.
• Extinct volcano


  A volcano that has not had an eruption for at least 10,000 years and is not expected to erupt again in a comparable time scale of the future.
• Examples of volcano types

  • Active volcano: Mayon, Hibok-Hibok, Pinatubo, Taal, Kanlaon, Bulusan
  • Dormant volcano: Mt. Makiling (Laguna), Mt. Iraya (Batanes), Mt. Alu (Sulu)
  • Extinct volcano: Mount Butay in Camiguin
• Landslide


  A massive outward and downward movement of slope-learning materials
• Landslide


  Restricted movements of rocks and soil masses
• Landslide


  Triggered by other natural hazards (prolonged rainfall)
• Landslide


  Caused by earthquake or volcanic eruption
• Landslide


  Susceptibility of hill slope is developed as a result of denudation of mountainsides
• Causes of landslide

  • Groundwater (pore water) pressure acting to destabilize the slope
  • Loss or absence of vertical vegetative structure, soil nutrients, and soil structure (e.g. after wildfire)
  • Erosion of the toe of a slope by rivers or ocean waves
  • Weakening of slope through saturation by snow melt, glaciers melting or heavy rains
  • Earthquakes adding loads to barely stable slope
  • Earthquake-caused liquefaction
  • Volcanic eruption
• Human causes of landslide

  • Deforestation cultivation and construction
  • Vibration from machinery or traffic
  • Blasting (As miners normally do)
  • Earthwork which alters the shape of slope or which imposes new loads on an existing slope
  • In shallow soils, the removal of deep rooted vegetation (e.g. kaingin farming system)
  • Construction works, agricultural or forestry activities (e.g. logging) which change the amount of water infiltrating the soil
• Effects of landslide


  • Property damage, injury and death and adversely affect a variety of resources like water supplies, fisheries, sewage disposal systems, forests, dams and roadways
  • Negative economic effects include the cost and repair structures, loss of property value, disruption of transportation routes, medical costs in the event of injury
  • Water availability, quantity and quality can be affected
  • Geotechnical studies and engineering projects to assess and stabilize potentially dangerous sites can be costly
• Sinkhole


  Can be human induced
• Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater
• Sinkholes are dramatic because the land usually stays intact for a while until the underground spaces just get too big
• Hydrometeorological


  A process or phenomenon of atmospheric, hydrological or oceanographic nature that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage
• Hydrometeorological hazards

  • Typhoon
  • Thunderstorm
  • Flood
  • Flashflood
  • Storm Surge
  • El Niño
  • La Niña
• Weather forecasting

  1. Observation

  2. Collection and Transmission of Weather Data

  3. Plotting of Weather Data

  4. Analysis of Weather Maps, Satellite and Radar Imageries and Other Data

  5. Formulation of the Forecast
• Thunderstorm


  A powerful, short-lived weather disturbance, almost always associated with lightning, thunder, dense clouds, heavy rain or hail, and fast, roaring winds
• Thunderstorm formation

  1. Cumulus Stage

  2. Mature Stage

  3. Dissipating Stage
• Flood


  A high-water stage in which water overflows its natural or artificial banks onto normally dry land, such as a river inundating its floodplain
• Types of floods

  • Inland flooding
  • Flash floods
  • River flooding
  • Coastal flooding
  • Urban flooding
• Storm surge


  The irregular sea-level rise during tropical cyclone or "bagyo" where powerful winds force the ocean water over the coastal low-lying areas, which can lead to flooding
• El Niño


  The large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific
• La Niña


  Periods of below-average sea surface temperatures across the east-central Equatorial Pacific
• El Niño effects


  • Diseases related to water scarcity or shortage such as diarrhea and skin diseases
  • Red Tide Blooms : Paralytic shellfish poisoning
  • Disorders associated with high temperatures: heat cramps, heat exhaustion, exertional heat injury and heat stroke
• La Niña effects


  • Disease related to contaminated water due to flooding, such as acute gastroenteritis, typhoid fever, cholera and hepatitis A
  • Disease related to wading in floodwaters contaminated with urine of infected animals, such as leptospirosis
  • Disease brought by mosquitoes, such as dengue and malaria
  • Accidents and injuries such as contusions, lacerations, fractures, electrocution
• Hydrometeorological hazards


  A process or phenomenon of atmospheric, hydrological or oceanographic nature that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage