Cascadia Subduction Zone by alicejenny

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									   Tectonics 3

Select Tectonic Regions
                   Divergent Boundaries
A typical divergent
    boundary like
those found in all
    of the world’s
oceans. Note the
    mirror image
  structure of the
ridge and classic
 rift valley directly
 over the magma
        source.
                             Iceland
Iceland is the only nation
  on Earth that rests on
     top of an active
divergent boundary. It is
  highly volcanic but no
 one pays for heating or
        hot water.
Iceland…Land of Fire and
          Ice
Iceland…Land of Fire and Ice
Heimaey Eruption of 1973
                Transform Boundaries




A typical transform boundary. Since there is no subduction, there
     are no resultant volcanoes. However. These areas are
   seismically very active. The San Andreas Fault is the most
               researched fault of this type on Earth.
  Much of the San
      Andreas is
 disguised beneath
surface features like
these in the Imperial
      Valley, CA.
 However, while the
 land on left side of
this photo slides SE,
   the right side is
     moving NW.
                  Convergent Boundaries
   Ocean to
    ocean
 convergence
common in the
Pacific Ocean.
   Note the
volcanic island
arcs that form
  above the
  subduction
    zone.
               Convergent Boundaries

 Ocean to continent
 convergence found
throughout the world
on active continental
    margins. The
      Cascadia
 Subduction Zone of
 the Western US is
   such a location.
                         Japan
   Japan sits atop
    the intersection
    point of 4
    separate tectonics
    plates
   The nation is one
    of the most
    earthquake
    riddled locations
    on Earth
                       The Caribbean
   The Caribbean
    owes its existence
    largely to
    convergent plate
    tectonics
   Many islands are
    still seismically and
    volcanically active
   Rare but massive
    eruptions have
    occurred

                            Tectonic map of the Caribbean region.
                            Green triangles indicate active volcanoes
                            while red crosses show seismicity.
The island of Montserrat was once
called the “Emerald Isle” until its
resident volcano erupted in July 0f
1995. Since that time, it has erupted
off and on and only the very northern
tip is still populated.
The impressive volcanism of Southeast Asia. The Tambora (1815) and
Krakatau (1883) eruptions are among the largest in recorded history.
      The US West Coast is
  geologically “alive” where all
three types of plate boundaries
 can be found. No less than 4
    major plates and several
 microplates are visible in this
map. Under tremendous stress,
   these plates have created
 widespread fault and fracture
 zones that are responsible for
    this region’s innumerable
  earthquakes. Further to the
North, the Cascadia Subduction
   Zone is responsible for the
  volcanic Cascade mountain
chain which runs from northern
     California into Canada.
Cascade Range Eruption History
The Cascade Range
         The famous May 18, 1980
         eruption of Mount St. Helens,
         the most recent “major” event
         in the Cascade Range.
                Convergent Boundaries

 Continent to
  continent
convergence
found in such
   areas as
  Nepal and
    Tibet.
              Continental to Continental
                    Convergence
   Rather rare
    occurrence
   Surface features often
    hide tectonic origins
   Responsible for the
    world’s highest
    mountain ranges
The Himalayas and Tibetan
        Plateau
              Future Plate Boundaries?
   The Great Rift
  Valley of Africa is
the longest rift zone
    on the planet.
   Stretching from
      Jordan to
 Mozambique, it is
  over 4000 miles
 long and contains
 many seismic and
  volcanic features
 including some of
 Africa’s mountains.
Future Plate Boundaries?




          Mt Kilimanjaro, Africa’s highest
          peak, stands at 19340 feet. It
            consists of three separate
          vents that converged after the
             mountain’s last massive
             eruptions ~300,000 YBP.
Comprehensive map with all plate boundaries placed next to
                 each other. (USGS)

								
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