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11.2 Summary: How Earthquakes and Volcanoes Shape Earth’s Crust (Pages 374-389)
1) Most geological processes take place very slowly, over _______________________ or
_________________________ of years, but some processes, like
__________________________, ______________________________, and
___________________________________ can happen very quickly and with very little
warning.
2) The rock of Earth’s crust is under pressure. When the pressure is too great, the rock breaks
suddenly, creating an ______________________ (the shaking of the ground).
3) A _______________________ is a special machine used to measure earthquakes. They are
attached to ________________________ (solid rock that lies beneath the soil) in order to
detect the vibrations that result from an earthquake.
4) The _________________________________ is a method of measurement used to describe
the strength of an earthquake. It starts at 1 and can go as high as necessary.
5) A __________________ is a break in rock layers. There are ___________________ kinds:
-________________ fault: produced at divergent boundaries; plates move apart; rock
from the fault moves downward.
-_________________ fault: produced at convergent boundaries; plates push together;
rock about the fault moves up and over rock below the fault.
-_____________________ fault: produced at transform boundaries; plates move
sideways past each other; rock breaks as the plates try to slide past each other.
6) ______________________________ are the energy waves that travel outward from the
source of the earthquake. These waves are actually smaller earthquakes and can cause
damage to continue.
7) The place deep in the crust where an earthquake begins is called the _________________ of
the earthquake. The surface location directly above the focus is called the
_____________________.
8) Most earthquakes along the _________________________________________________.
9) There are approximately ____________________ earthquakes in Canada each year, but
only a few of these are strong enough to be felt by people.
10) A _______________________ is an opening of Earth’s crust.
11) Volcanic eruptions have created valuable resources. _____________________ increases
soil fertility. __________________________________ heats groundwater. Volcanoes release
_________________ and _____________________________ from the interior of Earth, adding
important gases to our atmosphere.
12) Volcanoes can also be destructive. They can destroy homes, trees, crops, and landscapes.
The _____________ can travel great distances and cause breathing difficulties.
13) Most volcanoes are found along plate boundaries:
-Where plates collide at convergent boundaries, the part of the crust that is pushed
downward reaches very hot areas where it melts and becomes ___________________.
Eventually there is so much magma, it is forced up through openings and erupts.
-Where plates separate at ____________________ boundaries, magma flows up to the
surface.
-In areas where plates are _______________, magma can be forced through the cracks
to the surface.