Natural Hazards

1. Natural Hazards Patterns, Predictions and Mitigating Technology

2. Natural Hazards • A natural hazard is an event that occurs in nature that has the potential to cause harm to humans or their property. • There are two sources of natural hazards • Geological • Atmospheric

3. Natural Hazrds • Earthquakes • Volcanoes • Landslides • Rockfalls • Sinkholes • Avalanches • Blizzards • Flooding • Hurricanes • Lightning Storms • Tornadoes Geologic Atmospheric

4. Geologic Hazards Many are based off of the tectonic plate boundaries and other smaller faults • 3 Kinds of Plate Boundaries • Divergent • Convergent • Transform

5. Divergent Boundary • Are the result of “pulling” forces • Have small earthquakes • Create many normal faults • Are usually on the opposite side of the plate from a convergent boundary

6. Convergent Boundary • Collision of two plates • Have all the large earthquakes • 90% of all earthquakes happen here • Ocean-continent collisions = subduction • Explosive volcanoes • Reverse faults

7. Transform Boundary • Are the result of parallel and opposite forces • Have small to medium earthquakes • Create strike-slip faults • Can cause streams to turn at right angles

8. Transform Boundary • The Hayward Fault passes directly beneath both end zones at California Memorial Stadium, the home of football at the University of California, Berkeley. The site probably looked flat and easy to build on in 1922 before knowledge of earthquake faults was very advanced.

9. Earthquakes The shaking and trembling that results from the sudden movement of part of the Earth’s crust • Earthquakes form seismic waves which we can record using seismographs • Almost all are along the plate boundaries • The force travels out from the earthquake epicenter(the point on thesurface directly above theearthquake)

10. Earthquakes Seismographs • A balanced tool that when the earth shakes causes the pen to write on a moving wheel of paper. • Larger quakes produce larger amplitudes • The Richter scale lets us compare them for strength

11. Earthquakes • There is no way to Predict or Forecast an earthquake • We can determine how likely one is • An area of high risk has building codes that make structures safer in the case of an earthquake

12. Volcanoes An opening in the ground that erupts gases, ash and lava • Caused by plate movement along the boundaries • Occur at both divergent and convergent boundaries

13. volcanoes • Can be either an explosive eruption or a non explosive eruption • Explosive eruptions are measured on the Volcano Explosivity Index from 1 to 10, based off of amount of tephra (material) shot out and the height of the column

14. Volcanoes • Volcanoes are divided into 3 groups: Active, Dormant and Extinct • Before a volcano erupts it goes through a pre-eruption period • Increase in earthquake activity under the cone • increase in temperature of cone • melting of ice/snow in the crater • swelling of the cone • steam eruptions • minor ash erupt

15. Volcanoes • Currently no technological “fix” for volcanoes • Prediction is easy and buildings can be built to withstand the different hazards or more importantly built to avoid them

16. Landslides/Rockfalls • Happen in steep unstable areas • Mostly when there is large amounts of water • Large rainstorms, Fast snowmelt, etc

17. Sinkholes • Caused by heavy weight on soft soil, the pressure builds up until it collapses • Disturbances at the surface can trigger a collapse • Areas with bedrockmade of limestone,salt deposits orcarbonate rock are the most susceptibleas water dissolvesthose materials

18. Sinkholes

19. Atmospheric Hazards Result from the constant cycling of air (hot and cold) and water • More prevalent in areas that provide ample space for the conditions to build

20. Atmospheric Hazards • As temperatures have risen we have seen an increase in the number and size of atmospheric damages

21. Blizzards and Avalanches • A severe snowstorm with sustained winds of at least 35 mph and lasting typically 3+ hours • Can be larger than a state • Ground Blizzards are similar except it is not falling snow but snow blowing from the ground

22. Blizzards and Avalanches • Can be predicted using radar we can see the cloud formations and infrared imaging can show the air temperatures • Blizzards form when cold arctic air mixes with warm moist air(from tropics above large lakes) • No way to prevent a blizzard, best way to mitigate it is stay inside/stock up and then when it is over start cleanup

23. Blizzards and Avalanches • Avalanche • Rapid flow of snow and/or ice down a sloping surface • Caused when the snowpack loses cohesion (weight/disturbance) • Entrains more snow/ice/rocks/trees

24. Blizzards and Avalanches • Prediction – large snowfalls often lead to avalanches • Active Prevention • Constant travel, explosive charges Both cause minor avalanches before the buildup • Passive Prevention • Snow fences, trees,other foliage • Mitigation – in areas ofconsistent avalanchesDON’T build there,snow fences again

25. Flooding • A temporary overflowing of water onto land that is normally dry • Height of water could be only a few inches to above the tops of houses • Can happen slowly over days or suddenly (flash floods)

26. Flooding • Heavy Rain • Rapid snowmelt • Coastal storms • Storm Surge • Waterway overflow -blocked by debris/ice • Levees, dams, or waste water system • Anywhere, often in low lying areas near a body of water • Occur during every season but some areas have times of high risk (hurricane season, monsoon season, etc) Causes Locations/Time

27. Flooding • Preventing • Early Warning systems • Often reoccur in locations and time • Construction prevention – dikes, dams, levees • Often have no basements • Sandbagging

28. Flooding • Preventing • Early Warning systems • Often reoccur in locations and time • Construction prevention – dikes, dams, levees • Often have no basements • Sandbagging

29. Hurricanes • Hurricanes, Typhoons, Cyclones – same thing, names signify where the storm is located • If the wind speeds are only 35 mph (in one minute gusts) it is a tropicalstorm • If the wind hits 74+ mph(in one minute gusts) it isa hurricane • Hurricanes are named to avoidconfusion with another storm

30. Hurricane • Form over warm tropical waters and then are carried North or South by the prevailing winds(winds that move from the equator to the poles) • Warmer waters produce more and larger hurricanes • Can be predicted similar to blizzards by watching the cloud formation and temperature changes

31. Hurricane Hazards • Storm Surge/Tide • Heavy Rainfall/inland flooding • High winds • Rip currents • Tornadoes

32. Hurricane Mitigating Technology • Nothing can stop it • Evacuation often considered • Strengthen homes • Strengthen roof • Garage doors • Strengthen windows • Put away lawn chairs/outdoor furniture

33. Lightning Storm / Thunder storm / Electrical Storm/ thundershower • A storm characterized by lightning and the acoustics with it • Occur in a type of cloud called cumulonimbus • Accompanied by rain, hail, snow or nothing • Normally move withthe mean winddirection but mayturn at right angledue to wind sheer

34. Lightning Storm / Thunder storm / Electrical Storm/ thundershower • Result from the rapid rise of Warm moist air • As it rises the water condenses and forms raindrops, those raindrops fall and hit other ones growing in size • The collective fall of rain produces downdrafts

35. Lightning Storm / Thunder storm / Electrical Storm/ thundershower • Downdrafts cause the cloud to spreadout at the bottom • Collision with a warmer layer of air at the top blocks the rise and it spread out • Forming the signature “anvil” shape

36. A little mythology

37. Lightning Storm / Thunder storm / Electrical Storm/ thundershower • Risks from the other hazards that come with it • Tornadoes • Floods • Hail • Lightning of course • Grounding structures • Wild Fires • Stay away from tall objects • Faraday Cages

38. Tornado • Rapidly rotating column of air in contact with the ground and a cumulonimbus cloud • Scientists argue over if a tornado lifts off the ground and then makes another touchdown if it is another tornado or the same • Not always visible but the movement of the air can cause water vapor to condense into a cloud that moves with the wind

39. Tornado • The tornado is not actually the cloud funnel but the vortex of wind, often bigger than the funnel cloud • Tornadoes form when a mass of cold air collides with a mass of warm air, the warm air spirals up • Tornadoes take many forms or shapes

40. Tornado • Measured using Pulse-Doppler Radar • Often are hidden by rain • Measured using the Fujita scale or Enhanced Fujita which bases off the damage caused • US 1000 avg. • Canada 100 avg