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EARTHQUAKES
Practice for 6th grade quiz
Ms. Cooper’s class
Korematsu Elementary School
What does the term
“plastic” mean when
describing the upper
mantle?
Able to change shape
without breaking
What is a fault?
• A place on the Earth’s
surface that breaks
during an earthquake
Describe “stick-slip motion”
and tell what it causes.
When the crust of two plates
are stuck on each other.
Energy builds up and they
suddenly slip causing an
earthquake
What kind of energy builds up
when the crust of two plates
are stuck while the upper
mantle keeps moving?
Potential Energy
What is the point below
the surface where rock
breaks causing an
earthquake called?
The Focus
What do we call the point
on the Earth’s surface
during an earthquake
where the seismic waves
are the strongest?
The Epicenter
Where do shallow focus
earthquakes occur?
In the crust less than 50
km below the surface
Where do deep focus
earthquakes occur?
At subduction zones when
the plate breaks
What is a “slickensides”?
Exposed rock
that has been
polished from
another mass
of rock
moving
against it
Why is it better to have
frequent earthquakes along
a transform plate boundary
than seldom?
If earthquakes happen
frequently, the potential
energy can not build up
too high and there is less
damage.
Why do aftershocks
occur?
Because not all of the
potential energy is
released in a quake
What is an instrument that
measures seismic waves
called?
A seismograph
How do seismologists locate
the epicenter of an
earthquake?
• The difference between arrival time of P
and S waves are measured at THREE
seismic stations
• The distance of the quake from each
station is calculated
• A circle with the radius of that distance is
drawn around each station on a map
• The point where all three circles cross is
the epicenter
Which scale rates an
earthquake by the size of
its seismic waves?
The Richter Scale
Which scale rates the
damage suffered by
buildings, the ground and
people during a quake?
The Mercalli Intensity
Scale