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Webslide1.ldg

  1. 1. Geography Leadinggeographers.blogspot.com Geological And Natural Hazards https://leadinggeographers.blogspot.com
  2. 2. Objectives:  Define the terms tsunami.  List major types of geological hazards and describe ways to mitigate their impacts. https://leadinggeographers.blogspot.com
  3. 3. Define the terms tsunami.  Tsunami: An immense swell, or wave, of ocean water triggered by an earthquake, volcano, or landslide, that can travel long distances across oceans and inundate coasts. Japan Tsunami (March 2011) https://leadinggeographers.blogspot.com
  4. 4. List major types of geological hazards and describe ways to mitigate their impacts. • The circum-Pacific belt, or “ring of fire”, spawns most of the world’s volcanoes and earthquakes. • Earthquakes result from movement at faults and plate boundaries. We cannot prevent them, but we can build structures and cities in safer ways. • Volcanoes arise from heating by magma at rifts, subduction zones, or hotspots. • Landslides and other forms of mast wasting can occur on small or large scales; damage can be minimized by understanding their risks. • Tsunamis can flood coastlines and cause immense damage. Early warning systems will be key in minimizing future losses. • We often worsen impacts from natural hazards, but we can reduce them through better land use practices. https://leadinggeographers.blogspot.com
  5. 5. Geologic and natural hazards • Some consequences of plate tectonics are hazardous • Plate boundaries closely match the circum-Pacific belt – An arc of subduction zones and fault systems – Has 90% of earthquakes and 50% of volcanoes https://leadinggeographers.blogspot.com
  6. 6. Earthquakes result from movement • Earthquake = a release of energy (pressure) along plate boundaries and faults • Can be caused by enhanced geothermal systems – Drill deep into rock, fracture it – Pump water in to heat, then extract it • Can do tremendous damage to life and property https://leadinggeographers.blogspot.com
  7. 7. Volcanoes • Volcano= molten rock, hot gas, or ash erupts through Earth’s surface – Cooling and creating a mountain • In rift valleys, ocean ridges, subduction zones, or hotspots (holes in the crust) • Lava can flow slowly or erupt suddenly • Pyroclastic flow: fast-moving cloud of gas, ash, and rock – Buried Pompeii in A.D. 79 https://leadinggeographers.blogspot.com
  8. 8. Volcanoes have environmental effects • Ash blocks sunlight • Sulfur emissions lead to sulfuric acid – Blocking radiation and cooling the atmosphere • Large eruptions can decrease temperatures worldwide – Mount Tambora’s eruption caused the 1816 “year without a summer” • Yellowstone National Park is an ancient super volcano – Past eruptions were so massive they covered much of North America in ash – The region is still geologically active https://leadinggeographers.blogspot.com
  9. 9. Landslides are a form of mass wasting • Landslide = a severe, sudden mass wasting – Large amounts of rock or soil collapse and flow downhill • Mass wasting = the downslope movement of soil and rock due to gravity – Rains saturate soils and trigger mudslides – Erodes unstable hillsides and damages property – Caused by humans when soil is loosened or exposed • Lahars = extremely dangerous mudslides – Caused when volcanic eruptions melt snow – Huge volumes of mud race downhill https://leadinggeographers.blogspot.com
  10. 10. Mass wasting events can be colossal and deadly https://leadinggeographers.blogspot.com
  11. 11. Tsunamis • Tsunami = huge volumes of water are displaced by: – Earthquakes, volcanoes, landslides • Can travel thousands of miles across oceans • Coral reefs, coastal forests, and wetlands are damaged – Saltwater contamination makes it hard to restore them • Agencies and nations have increased efforts to give residents advance warning of approaching tsunamis – Preserving coral reefs and mangrove forests decreases the wave energy of tsunamis https://leadinggeographers.blogspot.com
  12. 12. One dangerous tsunami On December 26, 2004 an earthquake off Sumatra triggered a massive tsunami that hit Indonesia, Thailand, Sri Lanka, India, and African countries Killed 228,000 and displaced 1–2 million more https://leadinggeographers.blogspot.com
  13. 13. We can worsen impacts of natural hazards • We face and affect other natural hazards: floods, coastal erosion, wildfire, tornadoes, and hurricanes • Overpopulation: people must live in susceptible areas • We choose to live in attractive but vulnerable areas (beaches, mountains) • Engineered landscapes increase frequency or severity of hazards (damming rivers, suppressing fire, mining) • Changing climate through greenhouse gases changes rainfall patterns, increases drought, fire, flooding, storms https://leadinggeographers.blogspot.com
  14. 14. We can mitigate impacts of natural hazards • We can decrease impacts of hazards through technology, engineering, and policy – Informed by geology and ecology • Building earthquake-resistant structures • Designing early warning systems (tsunamis, volcanoes) • Preserving reefs and shorelines (tsunamis, erosion) • Better forestry, agriculture, mining (mass wasting) • Regulations, building codes, insurance incentives discourage developing in vulnerable areas • Mitigating climate change may reduce natural hazards https://leadinggeographers.blogspot.com

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