1. Plate Tectonics II:
Volcanos and Earthquakes and
Tsunamis, Oh My
Dr. Mark McGinley
Honors College and Department of
Biological Sciences
Texas Tech University
3. Evidence of Plate Tectonics
http://www.mnh.si.edu/earth/text/4_1_2_3.html
4. Evidence of Plate Tectonics
• 1980s
• Ten years of telescope-based
measurements from Earth to
distant quasars confirmed that
the North American and
Eurasian Plates are moving
away from each other at a rate
of 1.7 cm (0.7 in) per year.
• Geological studies of ocean-
floor rocks suggest the plates
have moved at this same
average speed for tens of
millions of years.
5. Evidence for Plate Tectonics
• Two telescopes — one in
Massachusetts, the other
in Germany — measured
their distance to a pulsing
quasar at the same time.
This measurement was
repeated 803 times over
10 years. Each point on the
graph indicates how far
apart the two stations
were at that time. As you
can see, they slowly
moved apart.
6. Plate Tectonics and Volcanos
• A volcano is an opening,
or rupture, in a planet's
surface or crust, which
allows
hot magma, volcanic
ash and gases to escape
from below the surface.
• Volcanoes are generally
found where tectonic
plates are diverging or
converging.
8. Volcanos and Divergent Plate
Boundaries
• A mid-oceanic ridge,
for example the Mid-
Atlantic Ridge, has
examples of
volcanoes caused
by divergent tectonic
plates pulling apart
9. Volcanos and Convergent Place
Boundaries
• http://geology.com/nsta/convergent-plate-
boundaries.shtml
10. Volcanos and Convergent Plate
Boundaries
• The Pacific Ring of
Fire has examples of
volcanoes caused
by convergent
tectonic
plates coming
together.
11. Volcanic Islands
• Not all volcanos
occur at plate
boundaries
• Hot spots, locations
of rising hot magma,
can cause magma to
reach the surface
causing volcanos
14. Earthquakes
• An earthquake is the result of a sudden
release of energy in the Earth's crust that
creates seismic waves.
• The seismic activity of an area refers to the
frequency, type and size of earthquakes
experienced over a period of time.
18. 1989 San Francisco Earthquake
• http://www.youtube.com/watch?v=zkx-
vO9I8r8&feature=related
19. Tsunami
• A tsunami is a series of water waves caused by
the displacement of a large volume of a body
of water, typically an ocean or a large lake.
• Earthquakes, volcanic eruptions and
other underwater explosions,
landslides, glacier calvings, meteorite
impacts and other disturbances above or
below water all have the potential to generate
a tsunami.
