Understanding Plate Tectonics
1. Plate tectonics is the study of the _______________ (motions & changes) of the Earth. ___________ in
the interior of the Earth drives plate tectonics. The Earths interior is estimated to be about _______ °C at
the core. The escaping heat from the center of the Earth drives the motions at Earth’s ___________.
2. Heat from the Earths interior ___________ upwards towards the surface where it escapes into space.
3. Convection is the mechanism that transfers heat through _________________. The Earth is made of a
________ inner core, a ________ outer core, a _______________ mantle, and a _________ crust. It is at
the thin crust where humans notice the effects of the heat of the earth’s interior in the guise of
_____________________________.
4. Heat escaping from the Earths interior has broken the Earth crust into nine major _______________ and
about a dozen minor plates. The boundaries of these plates are major fault zones. ________ are where
pieces of the Earth move relative to one another.
5. Plates move primarily in one of _______ ways. Where plates move apart they _____________. Where
plates come together they __________ or ___________. Collision occurs when plates of _________
density come together. Subduction occurs when plates of __________density come together.
6. There are ______ types of plates. Ocean plates are ______ and dense (heavy). Continental plates are
________ and less dense (light). Ocean plates are created at ____________ centers usually in the middle
of oceans. Ocean crust _________ as it is created and shuffles the movement of other plates as it bumps
into them.
7. Most of the world’s earthquakes and volcanoes occur at plate ______________. As ocean plates
subduct beneath continental plates ocean plates and overlying sediments melt and produce ___________.
Most plates creep slowly at a rate of about ___________. But they can move quickly and __________
causing massive movement and great earthquakes.
8. There are _________ primary types of earthquakes faults. ________________________ faults occur
when one block of rock slides past another. ______________ faults occur when one block of earth slide
below another block. _____________ faults occur when one block of rock moves over another. (thrust
faults)
9. On December 26th 2005 one of the world’s most recent great earthquakes occurred as the _________
plate subducted beneath the ___________ plate. This _____ magnitude event (a measure of the strength of
the earthquake) broke along ______ km (800 miles!) of the associated fault. The Indian plate which
normally moves at a rate of _________ jumped about 15 meters (10 feet!) in a matter of seconds releasing
an energy equivalent to ___________ atomic bombs and actually __________ some islands further out to
sea.
The sudden down drop of earth crust over such a wide area created a massive _________ (harbor wave)
which hit the coast of the entire Indian Ocean.
11. Tsunami’s occur as water is moved first offshore and then back onshore after a large _____________.
90 % of tsunamis occur in the _________ Ocean where an extensive __________ system exists. There is
____ tsunami warning system for the Indian ocean countries.
12. As the water initially moved out to sea during the earthquake many people were lured down to the
beach, but then were caught in the ____ foot wall of water that rushed inland at the speed of a
____________!
15. The human impact of the devastating earthquake and tsunami will affect countless lives for
__________________ to come.
16. On October 8, 2005 a massive ____ earthquake struck the mountain region of ________________
northwest of Islamabad killing over _______________ & injuring over 70,000. 4 million are homeless.
Pakistan borders the _______________ mountains that are being wedged up by the subduction of the India
plate under the ______________ plate. The majority of the damage was due to
__________________buildings collapsing on inhabitants. Disease, starvation, and ___________ will kill
many more people before the villages can be rebuilt.
18. Scientists cannot predict earthquakes or prevent them. But by measuring _________ along active
faults and studying their past _________ of movement they can assign __________ for future earthquakes.
In the _______________________ for example, one of the most actively studied seismic region in the
world with a growing population scientists have warned that a major earthquake is ________________.
Those who heed the warnings of scientists and __________ for the inevitable will be the ones who survive.