Natural Disaster Exam #1
Terms
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- Internal Processes
- Plate tectonics - identifies zones of possible earthquakes and active volcanism; identifies tectonic plates (large surface blocks of solid Earth) *Broken rock = fault
- "Ring of Fire"
- A major belt of volcanoes that rims the pacific ocean.
- Continents
- Are not defined by plate boundaries
- External Processes
- Atmospheric effects: Energy from the sun - Warms Earth's atmosphere and surface, produces wind circulation and water evaporation, and firms Earth's climate zones.
- Global Warming
- Causes rain clouds to move further inward providing rain for deserts instead of land
- Hazard
- poses threat to human life/property
- Disaster
- Results in significant damage, injury, loss of life
- Catastrophe
- requiring significant expenditure of time and money for recovery
- Landslide
- occurs after tsunami(s)
- Plate Tectonics
- Due to internal energy of the Earth; hot because of reactivity
- Earth's Internal Structure
- Inner core: hot and solid Asthenosphere: upper mantle; solid, hot magma with some flow Lithosphere: Thin, brittle crust; broken into plates that slip on asthenosphere; convection caused by push/pull of hot core on plates
- Two Types of Lithosphere
- Oceanic: dark, dense (i.e. basalt, iron, & magnesium) Continental: light, buoyant (i.e. granite, Potassium & Sodium silicate)
- Plate Boundaries
- dynamic events on Earth's surface occur when plates move (converge/slide past each other); plates aren't defined by oceans/continents, but where breaks occur (where earthquake is located)
- Divergent Plate Boundaries
- When plates move away from each other; new lithosphere is created; caused by convections; basalt comes up to form land
- Divergence b/w Two Ocean Plates
- causes mid-ocean ridges & seafloor spreading
- Convergent Plate Boundaries
- Subduction Zones: more dense ocean plates sink/melt; melted magma rises to form volcanoes Continental Collision Boundary: plates crunch together to form large mountains (ex: Himalayas)
- Transform Boundary
- plates slide past each other ("Humping"); mostly occur in ocean(s) Ex: San Andreas Fault (Strike-slip fault): Separates the Pacific from North American plate; connecting divergent plate boundaries
- Hot Spots
- area of magma that forms volcanoes/rocks; magma rises up from deep in mantle; stationary heat source located below lithosphere
- Magma vs. Lava
- M: below ground L: above ground
- Hydrologic Cycle
- process where water is purified and made fresh through evaporation and precipitation; solar energy drives movement of water b/w atmosphere/oceans/continents
- Biogeochemical Cycle
- combines all three cycles (rock, hydrologic, & tectonic); carbon, nitrogen, & phosphorous absorb infrared radiation heating atmosphere
- Soft-Story Building
- built like parking garages (or pancakes)
- Earthquake
- sudden movement of a block of Earth's crust along a geologic fault; movement released causes strain in rocks
- Earthquake Cycle
- proposition that a drop in elastic strain after an earthquake and a re-accumulation of strain before next event
- Strain
- deformation resulting from stress Elastic Strain: deformation that isn't permanent if the stress is eventually released
- Epicenter
- point on surface above focus (shallower the distance, the worse the earthquake)
- Focus
- point of initial breaking/rupturing within the Earth below the epicenter
- Moment Magnitude
- measure of total energy released; describes something physical about the earthquake Relation to Richter: MM bases finding on the physical aspect of the earthquake whereas the Richter scale measures the vibrations/waves beneath the Earth
- Richter Scale
- A scale that rates an earthquake's magnitude based on the size of its seismic waves using a Seismograph
- Seismographs
- records a zig-zag trace showing the varying amplitude of ground oscillations beneath instrument 2 --> 3= 10X's (ground displacement); 32X's (energy)
- Modified Mercalli Scale
- Based on damage to structures and people's perceptions (Women vs. Men - Dramatics); shows where damage is most severe
- Shake Maps
- use seismograph data to show areas of intense shaking; gives idea of magnitude
- Slip Rates
- movement along faults; measured in mm/yr
- Fault Types
- Dip Slip: vertical movement(s); more dangerous Strike Slip: Side-to-side; Horizontal
- Two Walls of Dip Slip
- Foot: Miners put their feet Hanging: Where they put their lanterns (Moves up/down)
- Three Faults of Dip Slip
- Normal: hanging wall moves down relative to footwall (gravity) Reverse: hanging wall moves up relative to footwall (thrust) Blind: Doesn't extend to surface
- Tectonic Creep
- Occurs when movement is gradual (earthquake isn't felt)
- Slow Earthquakes
- Movement along fault is small over a long period of time; there can still be large in magnitude with large area of rupture
- Types of Body Waves
- P (Primary): compressional waves; can go through liquid/solid; but can be refractured by liquid S (Secondary): shear waves; can't go through either (gets stopped by liquid)
- Surface Waves
- Love waves: moves along Earth's surface; travels slowly than body waves, both vertically and horizontally, responsible for damage near epicenter
- Love Waves
- Named for A.E.H. Love
- Distance to Epicenter
- measured by S-wave minus P-wave Ex: S-P=13 seconds, distance is 100 miles, and lag time is 50 seconds. 100 miles X 50 seconds / 13 seconds = 384.62 miles
- Depth of Focus
- deeper earthquakes produce less shaking than shallow earthquakes (closer to surface: the more "bang" it gets) Ex: Kirkbride example with 4th vs. 1st floor
- Location of Epicenter
- At least 3 stations are needed to find exact epicenter; intersecting part is the epicenter
- Liquefaction
- anything that shakes & becomes liquid; sand turns to liquid because it has pore spaces/holes
- Animals and Predicting Natural Disasters
- They have a more advanced set of senses that can sometimes predict when a specific natural disaster is coming. Ex: Elephants and tsunamis/earthquakes