Download Chapter 8 Sections 1-4

Chapter 8
Sections 1-4
By:
Kelsey Garrison
Brittany Ramsey
Seismology
• The study of earthquakes. The scientists who
study the earthquakes are called
seismologists.
Fault
• A breAk in the eArth’s crust Along
which blocks of the crust slide
relative to one another.
Earthquakes occur along faults
due to this sliding.
Deformation
• The change in the shape of a
rock in response to stress.
Rock along a fault deforms
mainly in two ways-in a plastic
manner, like a piece of molded
clay, or in a n elastic manner,
like a rubber band.
Elastic rebound
• The sudden return of elastically
deformed rock to its original shape.
Elastic rebound occurs when more
stress is applied to rock than the rock
can withstand.
Seismic waves
• Waves of energy that travel
through the earth. Different
types of seismic waves travel at
different speeds and move the
materials that they travel
through differently.
P waves
• Travel through solids, liquids,
and gases-fastest seismic
waves. Because p waves are
always the first seismic waves
to be detected, they are also
called primary waves.
S waves
• Shear waves-second fastest seismic wave.
Also, S waves are slower than P waves and
always arrive second; thus, they are also
called secondary waves.
Seismographs
• Are instruments located at or near the surface
of the earth that record seismic waves.
Seismogram
• A tracing of earthquake motion
created by a seismograph.
Seismologists use seismograms to
calculate when an earthquake
started.
Epicenter
• The poinT on The earTh’s
surface directly above an
earthquakes starting point.
The most common method by
which seismologists find an
earThquake’s epicenTer is The
s-p-time method.
Focus
• The point inside the Earth where an
earthquake begins.
Gap hypothesis
• States that sections of active
faults that have had relatively
few earthquakes are likely to be
the sites of strong earthquakes in
the future.
Seismic gaps
• The areas along a fault where relatively
few earthquakes have occurred.
Moho
• A place within the Earth where the speed of
seismic waves increases sharply. It marks the
boundary between the Earth’s crust and
mantle.
Shadow zone
• An area on the Earth’s surface where no
direct seismic waves from a particular
earthquakes can be detected.