Geography Tectonic hazards

    Cards (15)

    • What happens at tectonic plate margins
      1. Constructive margin: Plates move apart, magma forces way to surface, causes mild earthquakes, results in broad flat shield volcanoes
      2. Destructive margin: Plates move towards each other, dense oceanic plate subducted beneath less dense continental plate, friction causes strong earthquakes, results in steep-sided composite volcanoes
      3. Conservative (transform) margin: Plates move past each other at different rates, friction builds stresses and triggers earthquakes, no volcanoes
    • Constructive margin
      • Mid-Atlantic Ridge
    • Destructive margin

      • West coast of South America, Peru-Chile trench
    • Conservative (transform) margin

      • San Andreas Fault
    • Plates separate at constructive margins causing mild earthquakes and volcanic eruptions
    • Plates collide at destructive margins causing strong earthquakes and violent volcanic eruptions
    • Plates slide by at conservative margins causing powerful earthquakes
    • Monitoring volcanoes
      • Remote sensing, seismicity, ground deformation
    • Monitoring earthquakes
      • Microquakes before main tremor, bulging of ground, raised groundwater levels
    • Accurate earthquake predictions are impossible due to lack of clear warning signs
    • Historical records can help determine earthquake probability and aid planning
    • Protecting against volcanoes
      • Earth embankments and explosives used to divert lava flows
    • Protecting against earthquakes
      • Earthquake-resistant construction
    • Planning for volcanoes
      • Risk assessment and hazard mapping to identify areas for evacuation or building restrictions
    • Planning for earthquakes
      • Risk assessment and hazard mapping to identify areas to protect buildings and infrastructure
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