8th grade Science Study Guide – Earthquakes
 Seismology is the science in which earthquakes are studied.
 A seismologist is a scientist that studies earthquakes.
 Seismologists use a seismogram to determine when an earthquake
started.
 The focus is the place within the Earth where an earthquake begins.
 The epicenter is the place on the Earth’s surface directly above an
earthquake’s starting point.
 A seismograph is an instrument located at or near Earth’s surface that
records seismic waves.
 A seismogram is the tracing of earthquake motion made by a
seismograph.
 Seismologists use the Richter magnitude scale to measure the strength
of an earthquake.
 The measure of the strength of an earthquake is called the earthquake’s
magnitude.
 The degree to which people feel an earthquake and how much damage
it causes is called the earthquake’s intensity.
 The measurement of how likely an area is to have damaging
earthquakes is called earthquake hazard.
 The Gap Hypothesis states that active faults with few earthquakes in
the past will have strong ones in the future.
 If you are indoors when an earthquake strikes you should immediately
lie under a table and cover your head.
 If you are outdoors when an earthquake strikes you should immediately
go to a place away from buildings and trees, lie face down, and cover
your head with your hands. Do not run back into your home.
 To prepare for an earthquake before it happens, you should safeguard
your home, plan a place to meet others, and store food, water, and other
useful things.
 Convergent boundary = motion that happens when two plates push
together.
 Transform boundary = motion that happens when two plates slip past
each other.
 Divergent boundary = motion that happens when two plates pull away
from each other.
 During elastic rebound, the energy released travels as seismic waves in
all directions from the focus.
 Rock that deforms like a stretched rubber band is an example of elastic
deformation.
 A thing that acts like a shock absorber in an earthquake-resistant
building is a base isolator.
 Flexible pipes are used in earthquake-resistant buildings to help prevent
waterlines and gas lines from breaking.
 A common way to retrofit an older home is to be sure that it is securely
fastened to its foundation.
 A mass damper is a weight in the roof of a building that can shift to
counteract the movement of the building during an earthquake.
 P waves are the fastest waves. They are also known as primary waves.
 S waves are slower than P waves. They cannot travel through liquid.
They are also known as secondary waves.
 P and S waves are body waves. Body waves are waves of energy that
travel through the inside of the Earth.
 Surface waves are the most destructive seismic waves.
 An earthquake with a magnitude of 5.0 is 10 times stronger than an
earthquake with a magnitude of 4.0.
 The intensity of an earthquake is usually highest at the epicenter.