© 2011 Pearson Education, Inc. Earth’s Physical Systems: Matter, Energy, and Geology Geological And Natural Hazards AP Environmental Science Mr. Grant Lesson 21

© 2011 Pearson Education, Inc. Objectives: Define the terms tsunami. List major types of geological hazards and describe ways to mitigate their impacts.

© 2011 Pearson Education, Inc. 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. Define the terms tsunami. Japan Tsunami (March 2011)

© 2011 Pearson Education, Inc. 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.

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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 Buildings can be built or retrofitted to decrease damage

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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 supervolcano -Past eruptions were so massive they covered much of North America in ash -The region is still geologically active

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. Mass wasting events can be colossal and deadly

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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

© 2011 Pearson Education, Inc. 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