M 7'8 Earthquake Near Colima, Mexico - PowerPoint PPT Presentation

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M 7'8 Earthquake Near Colima, Mexico

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Shallow earthquake occurred in a seismically active zone. Occurred near the juncture of ... Pairs of magnetically reversed stripes on the floor of the ocean. ... – PowerPoint PPT presentation

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Title: M 7'8 Earthquake Near Colima, Mexico


1
M 7.8 Earthquake Near Colima, Mexico
  • Wednesday, January 22, 2003 at 20635
  • Shallow earthquake occurred in a seismically
    active zone
  • Occurred near the juncture of three tectonic
    plates
  • Killed 23 people

2
Are These Earthquakes Common?
3
Data from the Earthquake
  • Seismograms record ground shaking
  • Record of displacement as a function of time
  • Tell us all we know about earthquakes

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Plate Tectonics
  • Physical Geology 3101

7
Continental Drift theory
  • Fit of the continents
  • Apparent magnetic polar wandering
  • Unique rocks match (coal, glaciers...),
  • Unique fossils match,
  • Problem how did the continents drift?

8
Sea Floor Spreading
  • Pairs of magnetically reversed stripes on the
    floor of the ocean.
  • The oceans are much younger than the continents
  • The sea floors get younger toward the mid oceanic
    ridges.

9
Plate Margins
  • Lithospheric plates, 100 km thick
  • Geologic activity at margins
  • divergent,
  • convergent
  • transform

10
Divergent boundaries plates move away from each
other
  • A. Mid-ocean ridge spreading centers
  • 1. Create new oceanic lithosphere
  • 2. Gentle, basalt lava volcanoes
  • 3. Shallow (lt10km) small/med. earthquakes
  • 4. Iceland, mid-Atlantic Ridge
  • B. Continental rift
  • 1. Tears continent in two to create an ocean
  • 2. Rio Grande Rift, East Africa

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Divergent Boundary
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Convergent margins
  • Subduction Zones
  • Oceanic-Oceanic
  • Oceanic-Continental
  • Collisions
  • Continent-Continent boundaries

17
Subduction Zones
  • Destroys ocean lithosphere, ocean plate subducted
    under other plate and melts
  • Explosive volcanoes
  • Island arc (Philippines, Aleutians)
  • Volcanic arc (Andes, S. Mexico)
  • Huge deep earthquakes (lt700km),

18
Parts of subduction zones
  • Trench
  • Subduction complex
  • Volcanic arcs
  • Back-arc basin

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Oceanic-Oceanic
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Convergent Boundary
Ocean-Continent
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Oceanic-Continental
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Continent-Continent
  • Huge mountains
  • No volcanoes
  • Lots of earthquakes
  • Folded rocks, continents are joined together
  • Himalayas, Alps

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Continent Collision
29
Convergent Boundary
Continent-Continent
30
Transform plate margins plates slide past each
other, side-by-side
  • No volcanoes
  • Earthquakes with variable depths
  • San Andreas Fault

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Oceanic Transform
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Transform Boundary
36
Hot spots
  • Plumes of hot material from the mantle
  • Can show the absolute rate of plate movement.

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Most geologists believe that convection drives
plate tectonics.
  • Thermal convection cell

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Group Exercise
  • COOPERATIVE - One set of answers from the group,
    everyone has to agree
  • CRITERIA FOR SUCCESS -- Everyone must be able to
    explain the procedure used to solve the problem.
  • INDIVIDUAL ACCOUNTABILITY -- Random selection to
    give answers.
  • EXPECTED BEHAVIORS -- Everyone should
    participate, encourage each other
  • PROCESSING -- List three things you did well as a
    group. List one thing you can do better tomorrow.

44
Question
  • What is a tectonic plate?
  • What are the type of plate boundaries?
  • Define all sub-types boundaries
  • What plate to we live on?
  • What where the key observations that were used to
    come up the the theory of plate tectonics?
  • What drives the plates?
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