Module 2 Week 3 Tectonic Features

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  • 1. Tectonic Features Orogeny, Volcanism, and Earthquakes
  • 2. Overview
    • Orogeny
      • Plate Boundaries and Mountain Building
    • Volcanism
      • Types of Volcanoes
      • Properties of Volcanoes
      • Plate Boundary Associations
    • Earthquakes
      • Earthquakes and Faults
      • Earthquake Properties
      • Earthquake Damage
  • 3. Orogeny
    • Important orogenies
      • Allegheny Orogeny: Appalachian and Ozark Mountains; 250 – 300 million years ago
      • Sierra Nevadan Orogeny: produced the Sierra Nevada; 130 –160 million years ago
      • Alpine Orogeny: produced the Alps; 20 –120 million years ago
      • Laramide Orogeny: produced Rocky Mountains; 40 – 80 million years ago
      • Himalayan Orogeny: Produced the Himalayas; 45-50 million years ago
  • 4. Types of Orogenies
    • Associated with subduction zones
    • Oceanic plate-continental plate collisions
      • Andes, Sierra Madre, Rocky Mountains
      • Folded sedimentary strata, igneous intrusions, terranes, volcanism
    • Oceanic plate-oceanic plate collisions
      • Produce volcanic islands
      • Most of the islands arcing around the Pacific Rim; Indonesia, Aleutians, Japan
    • Continental plate-continental plate collisions
      • Himalayas, Alps
      • Intense folding, overthrusting, faulting and uplifting
  • 5.  
  • 6.  
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  • 8.  
  • 9.  
  • 10. Volcanoes
    • Volcanic landforms
      • Cinder cones, calderas, shield volcanoes, plateau basalts, composite volcanoes
      • Calderas form on any volcano when the original structure collapses
    • Locations of volcanic activity
      • Subduction boundaries (c-o, o-o)
      • Seafloor spreading and rifts
      • Hot spots
    • Types of eruptions
      • Effusive
      • Explosive
    • Eruption material
      • Lava
      • Pyroclastic material (tephra): ash, dust, cinders, scoria, pumice and aerial bombs
      • Gases
  • 11. Effusive Eruptions
    • Gentle eruptions producing mostly lava and gases
      • magma direct from the asthenosphere
      • low-viscosity and fast flowing
      • produces basalt
    • Landforms
      • Shield Volcanoes
        • gentle slopes, gradually rising to a summit crater
        • Often associated with hotspots
      • Plateau Basalts
        • Associated with rifts
        • Magma spreads out across surface
  • 12.  
  • 13.  
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  • 18.  
  • 19. Explosive Eruptions
    • Violent, explosive eruptions
      • Associated with subduction zones
      • Thick, viscous magma rising from subducted plates clogs vents in the volcano, allowing gases to build up to an explosion
    • Landforms
      • Cinder cones
        • less explosive eruptions
        • pyroclastic material builds up into a conical shape
      • Composite volcanoes (stratovolcanoes)
        • More explosive
        • Eject alternating layers of lava and pyroclasts, creating composite strata
        • Steep sides, conical shape, often very symmetrical
        • Mt. St. Helens
  • 20.  
  • 21.  
  • 22.  
  • 23. Earthquakes
    • Caused by motion along faults
      • Elastic rebound theory
        • Friction holds fault blocks motionless until strain exceeds friction
        • Sudden motion, at a point ( asperity ), releasing energy
      • The point in the earth where the slippage occurs is called the focus
      • The point on the surface directly above the focus is called the epicenter .
    • The strength of an earthquake felt at any given point depends on
      • Depth to the focus
      • Distance to the epicenter
      • Amount of energy released
      • Geological material; bedrock is better than loose sediments because of liquefaction
  • 24.  
  • 25. Surface Fault Epicenter Focus
  • 26. Measuring Earthquakes
    • Mercali scale
      • 1902
      • Intensity
      • Qualitative
    • Richter scale
      • 1935
      • Wave Amplitude
      • Quantitative
        • Logarithmic: each number represents a ten fold increase in amplitude, and a 31.5 increase in energy.
    • Moment Magnitude scale
      • 1993
      • Fault slippage, surface disturbance, geologic material
      • Quantitative
  • 27.  
  • 28.  
  • 29. After-Affects of Earthquakes
    • Topographic changes in elevation
      • Valdiva, Chile, 1960: 400 km 2 area dropped 7–9 meters
    • Tsunamis
      • Tallest measured wave: 70 meters
      • December 26, 2004 – Indian Ocean
        • 9.0 Magnitude quake off of Sumatra moves the island 150 ft West
        • triggered a tsunami with a large inland surge
        • Quake and Tsunami combined killed over 250,000 people
    • Catastrophic rockslides
    • Landslides