Natural Disasters

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Natural Disasters
2012-01-27 18:30:58

Natural Hazards, Continental Drift, Earthquakes
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  1. Natural Hazard
    Earth proces that, upon interaction with human activity, causes loss of life and property
  2. Human Element
    • without it there would be no hazard
    • because of it, science of geohazards become more important every year
  3. Earth's Population is Increasing
    • more people living in hazard prone areas (disasters are becoming more frequent and since population is growing, more people move to marginal lands)
    • populations becoming hyper-concentrated
    • consumption of resources
    • 50% of the population lives in cities -> increase to 70%
  4. Tsunami in Japan
    Yuriage, Natori
  5. CANNOT Stop
    • geologic processes
    • population growth
    • can't lessen disasters
  6. CAN
    • must try to mitigate hazards
    • changes in engineering practices (buildings)
    • aducating people
    • management plans
  7. Types of Natural Disasters
    • Volcanoes, floods, earthquakes, storms, landslides, tsunamis, hurricanes, meteorites
    • can ccur ith or without warning
    • precoursers can occur
  8. To mitigate hazard you need to know...?
    • Frequency vs. magnitude
    • F: How oftern a given event occurs in a certain region
    • M: how powerful (amount of energy released)
    • Scope: area affected by a given hazard
    • local
    • regional
    • global
  9. Why do earthquakes occur?
    Seismic energy is usually caused by brittle faults
  10. San Francisco earthquake
    • magnitude 7.7 - 8.3
    • epicenter 2 miles offshore of San Francisco
    • Huge fires
  11. Haiti
    Magnitude of 7.0
  12. Earthquake Hazards
    • kills the highest number of people per year
    • strike without warning
    • no time for evacuation
    • not a predictable trend to earthquake numbers, magnitude or location
  13. Mitigate hazard from Earthquakes?
    • Reinforce buildings
    • education
    • disaster plan -> minimize casualties
  14. Second largest recorded earthquake
    Sumatra - earthquake occured at a convergent boundary
  15. 2011 Japan tsunami
    • Biggest earthquake in Japan in 1,200 years
    • magnitude 9.0
    • 33 ft high waves
    • five continuous minutes of shaking
  16. Mitigate tsunami hazards?
    • monitoring
    • building restrictions in hazard prone areas (hilo harbor and downt)
    • Seawall construction
    • cause early wave breaking
    • prevent wave run up into urban areas
    • Education
    • warning
    • evacuation
    • general understanding (run to high ground)
  17. Tropical Cyclones
    • Bangladesh -> Gorgi
    • Most widespread destructive weather hazard
    • Saffir Simpson Hurricane Scale categories (1-5)
  18. Hurricane Katrina
    most costly and most deadly in US history
  19. Hurricaine Katrina damage produced?
    • storm surge
    • wind
    • -loss of power
    • flying debris
  20. Mitigate Cyclone/ Hurricane hazards?
    • Monitoring
    • Infrastructure (place for evacuation)
    • Education and planning
  21. Geology
    • earth concentrates energy
    • release energy violently
  22. Creation of the Universe
    • 115BA
    • The big bang thoery -> compressed matter which exploded and has been expanding in the universe ever since
    • expanding and shifting towards the red end of the spectrum (red shift)
    • Explosion/ Contraction
    • Contraction -> when the light shifts to the blu/ violent of the of spectrum
  23. Milky Way Galaxy
    • World is in this galaxy (3/5 out in one of the arms)
    • Spiral Shape
    • Two arms
    • 100 thousand years across (240 billion stars)
    • Flattened disc and central bulge
  24. Solar System
    • Pluto -> to small and orbit is different (NOT part of the system)
    • We are in a second generation star
    • Saturn, Jupiter, Earth, Moon, Mercuy, Venus, mars, Uranus, Neptune
    • Gravity -> the attraction between objects
    • Earth 3rd planet out
  25. Planetary Accretion
    • Showing (growing of the planets -> caused by gravity)
    • (a) the formation of planetesimals from the dust of the solar nebula and
    • (b) the formation of planets through the impacting and accretion of planetesimals
  26. Earth
    • Average terrestrial planet (mercury, venus, earth)
    • Jovian planets (accumulation of gas)
    • Free water -> only planet that has a vast amount
    • Plate tectonics -> inside of planet is hot -> outside is cold
    • Three types of rocks
  27. Ocean and Atmophere
    • gravity pulls the heaviest to the center -> created the core iron/nickle
    • planetary differentiation
    • core/ mantel (liquid causes plate tectonics) / crust
    • layering out of earth due to gravity by density
    • Lightest outgassed from volcanoes
  28. The Rock Cycle
    • Sedimentary
    • Metamorphic
    • Igneous
  29. Hydrologic Cycle
    • Exogenic Cycle -> gets energy from the sun
    • Heat to evapurate
    • rivers/ flooding
  30. Carbon Cycle
  31. Phosphorous Cycle
  32. Tectonic Cycle
    • impact of asteroids during planetary accretion
    • decay of radiocative elements -> Heat
    • gravitational contraction -. friction between monucules -> Heat
  33. Another Factor in Natural Disasters?
    • Gravity
    • Every particle attract other particles
    • g = a X b -> gravity is proportional to the mass of the two particles
    • g= 1/d^2 gravity is inversly proportional to the squared distance of the two objects
    • Sun affects less because its father from the earth compared to the moon
    • g = Gab/d^2
    • *G = universal gravitational constaant
    • This force holds the universe, solar system, EVRYTHING together but it can also tare things apart
  34. Chemistry
    Atom -> Molecule -> Mineral -> Rock
  35. Atomic Configuration
    • atoms fill outer shell with electrons e-
    • BONDING -> atom donates to another atom its electron
    • (ionic/ covelant) Ionic bonding
    • Covalent Bonding
    • form by sharing electrons
    • Bodning creates minerals
  36. Mineral
    • Solid (ice)
    • Naturally occuring
    • Homogenous -> minerals the same throughout
    • Inorganic
    • Specific chemical composition
    • Specific structural arrangement (crystal/pattern)
  37. Continental Drift
    • 1915 Alfred Wegener - Pangea
    • Theory of continental drift and developed lines of evidence to his theory
    • Theory failed because he did not provide a mechanism
  38. (1) Fit of the continents
    It looks like the continents fit together
  39. (2) Fossil Evidence
    Animals interbreed before the continents separated
  40. (3) Rock Type Similarities
    • Igneous needs a common source
    • Metamorphic
  41. (4) Paleoclimatic Evidence
    • Sedimentary rock
    • Mirrors climate across the world
    • tropical regions (coral reefs)
    • Deserts 30 degrees above and below the equator
    • water sorted based on the size of the sediments
  42. Harold Jeffreys - Physicist
    • Wegner failed to provide a physical mechanism, to explain the movement of huge boulders to other areas
    • Wegner finds a mechanism - the gravitational pull of the moon towards earth moved the boulders
  43. Fast Foward to 1950's
    Old magnetism: there are stripes on the sea floor that goes from normal to reveerse polarity as you go across the ocean
  44. Earth's Magnetc Field and Geomagnetic Reverals
    • Magnetic field S -> N (reverse polarities)
  45. Seafloor Sediment Distribution
    Sediment is laying in order from oldest to the newest
  46. Seaflor Spreading
    There is a volcanic chain of mountains under water that goes from the North Pole to the South Pole
  47. The Earth's Magnetic Field
    • When it cools they develop magnet and when magnetic field reverse than it changes polarization
    • Sea floor is basalt (magnetite) when hot, poles are straight up
    • Mariana trench is the deepest trench on earth
  48. Hot Spots
  49. Apparent Polar Wander
    When continents were put to fit together the pole matched a common pole
  50. Earthquake and Volcano Distribution
    • Concentrated along brittle boundaries
    • Most earthquakes happen along the ring of fire
  51. Plate Tectonics
    • Motion of the plates composing the Earth's lithosphere through subduction and seafloor spreading
    • Lithosphere (rocky part of land) broken into plates, riding around like bumper cars
    • Movement due to HEAT differential within Earth
    • The edge of a continent may or may not consist with a plate
  52. Mechanisms
    • Convection Cells (liquid portion) Mantel
    • Cold = More Dense = Sink Down
    • Hot = less dense = rise up

  53. Hot Plumes
  54. Ridge Push and Slab Pull
    • Lithosphere
    • Slab pull will cause land to converge, go underneath the lithosphere
    • Push new layers
  55. Plate Boundaries
    • Convergent - mountain/ island volcanoes
    • The colder (ocean plate) and denser will go under and melt
    • Divergent - coming apart
    • Transforming Boundaries -
  57. Earthquakes
    Not Random -> Collections of them around tectonic plates
  58. Subduction surface causes
    the worse earthquakes
  59. What ARE earthquakes?
    • Rapid slip along the fault
    • the elastic failue of the rock
    • the stronger the rock the stronger the earthquake
    • earthquakes can be seismic waves that come from the focus
    • longer the time the force is applied = bend
    • shorter time the force is aphe confiding pressureplied = break
    • the confiding pressure
    • temperature elastic behavior/ elastic failure
  60. What is Plotted on a Map?
    • Focus the physical position inside the earth
    • Draw a line straight up from the focus it's the epicenter
    • Fault the surface expression of the brakeage thrust fall
  61. Why are Earthquakes Interesting?
    • 1. Destruction/ high death toll
    • 2. Informationt About Earth's Interior - track earthquake and waves are received by seismometers, found about the temperature of the interior layers of the earth and the rock context
    • 3. Seismology - valuable information about the shallow surface, where there are faults, oil and water sources
    • 4. Formation & Exposure of Mineral Resources
    • Copper was exposed through a fault
    • 5. Contribution to GW and energy resources
    • Oil Pools
  62. What Happens in an Earthquake?
    • Building swaying/ pancaking
    • Fire and explosion from fuel tanks and lines
    • San Francisco huge fires
    • Lisban, Portugal earthquake that caused a huge fire -> tsunami
    • Liquefaction of sand and clay
    • House, building, roads sink into the ground
    • Landslides after the earthquake
    • Philippines
    • Tsunamis
    • The after affects are the worse
  63. How Big are Earthquakes?
  64. Orginal Mercalli Scale
    • quantified earthquakes in roman numerals
    • failed because of different levels of expertise/ human structure isn't always present/ depending material of buildings
    • I: least damage - XII: worst damage
  65. Modified Mercalli Scale
    used today, shaking intensity to factor the geological material
  66. Rictor Scale
    was created for a specific area in San Francisco
  67. Movement Magnitude Scale
    • is a logarithmic scale of energy release
    • Inverse relation between magniture and frequency
    • The bigger they are the less frequent they happen
  68. How do we measure seismic waves?
    • P- compressional waves (fastest): the bunching up and expanding of waves
    • S- Shear waves (hit next): more damaging than the P waves
  69. Surface Waves
    boundary between two media with different physical propertis (love and raleigh) SLOWEST but MOST DAMAGING
  70. Ancient Chinese Seismograph
  71. Horizontal Seismograph
    • P -> S -> Surface (doesn't include the large movements the can't be captured by the width of the paper)
  72. Press Ewing Model
    will get the 3 dimesional of the movement
  73. What is generated? Seismogram
    • Radius of the circle s it can be anywhere within the radius
    • Triangulation- network of seismographers
    • Northeastern has a seismographer
  74. Earthquake prediction: it's an ART
    • 1. Animal behavior: drop pressure, protp P wave can be identified
    • Dogs
    • Cats
    • Snakes
    • Aquatic Birds
    • Horses
  75. 2. Historical Record
    Stick- Slip Behavior (Kobe, Japan 1995)
  76. 3. Trenching
    • Disturbance layers tells you frequency
    • Wetlands are region of constant of plant accumulation, pattern of inter-fingering and they knot up at the surface area, helps extend the historical record
  77. 4. Seismic Gaps
    • Parkfiel, CA 6.0 there will be another earthquake in Parkfield, California and it will be big
    • Grey constant small earthquakes
    • Red strained rocks, huge earthquakes even though less often
  78. 5. Changes in rocks
  79. 6. Dilation picked up by stain
    some change from water
  80. Factors Controlling Damage
    • 1. The farther distance from epicenter the less damage
    • 2. What is the Local Geology?
    • San Francisco Marina District
    • Unconsolidated sediment fill which is not safe to build on
    • 3. Construction Methods
    • How is your house built? (structural integrity)
    • Mud, straw with heavy roof = BAD amplified movement
    • Concrete with steel reinforcements = GOOD
    • 4. Population, Density, Time of Day
    • How many people are there?
    • Where are they concentrate?
  81. Prediction: Bottom Line
    • We're learning that we can cause earthquakes by lubricating the faults, putting waste in our faults
    • EQ's still very damaging and unpredictable
    • Interesting proposal - Colorado, Rocky Mountain Arsenal
    • Alaska most earthquakes
  82. Areas of Lower Seismic Risk
    Boston is one of them
  83. Pacific Northwest
    • Subduction zone earthquakes (convergent boundary)
    • Juan de Fuca Plate -> North American Plate
    • Caused the Seattle Needle to shake
    • a pull apart area and the atlantic is a passive and moves along
  84. Basin and Range
    • Arizona and Nevada
    • Continental Rifting
  85. Hawaii
    • Volcano- related
    • stic- slip behavior of the edges of the magma cooling
    • Small earthquakes
  86. Mississippi River Valley 6.8
    • Ancient rift zone! (Reelfoot rift)
    • Divergent
    • New Madrid Earthquake rang the bells in Boston
  87. New England (moderate seismic activity)
    • Near future there will be a huge earthquake
    • Glacial rebound?
    • Lithosphere that is used to a lot of pressure and it is doing a stick/ slip behavior
    • Old pluton related?
    • A pulse of magma which can cause a popping upwards
    • Reactive of a rift system?
    • SW/ NE regional compression?
    • Squeezing of rocks will cause a popping upwards
    • Fracture zone movement
    • Stretching out of rock can cause a fracture
    • Big ONE? Yes geologist have confirm a big earthquake
    • Small earthquakes every other day
    • Area of moderate seismic activity