Download Chapter 8- Earthquakes

Chapter 8- Earthquakes
By Samantha Pereira
Summary of Chapter
• This chapter will tell you how
earthquakes form, the different
types of motion during an
earthquake, how to measure
an earthquake, and what we
do in earthquakes.
Lesson 1- What Are Earthquakes?
Lesson 1 Vocabulary
• Seismology- the study of earthquakes
• Deformation- the bending, tilting, and breaking
of Earth’s crust
• Elastic rebound- the sudden return of elastically
deformed rock
• Seismic waves- a wave of energy that travels
through the Earth
• P wave- a seismic wave that causes particles of
rock to move backward
• S wave- a seismic wave that causes particles of
rock to move in side-to-side manner
Lesson Summary
• Earthquakes occur mainly
in the edges of tectonic
plates.
• Elastic rebound is the
direct cause of
earthquakes.
• Three major types of
faults occur at tectonic
plate boundaries: normal
faults, reverse faults, and
strike-slip faults.
Lesson 2- Earthquake
Measurement
Lesson 2 Vocabulary
• Seismograph- an instrument that records
vibrations in the ground and determines the
location and strength of an earthquake
• Seismogram- a tracing of earthquake motion
that is created by a seismograph
• Epicenter- the point on Earth’s surface directly
above an earthquake’s starting point, or focus
• Focus- the point along a fault at which the first
motion of an earthquake occurs
Lesson Summary
• Seismologists detect
seismic waves and
record them as
seismograms.
• The S-P time method
is the simplest
method to use to find
an earthquake’s
epicenter.
Lesson 3- Earthquakes and Society
Lesson 3 Vocabulary
• Gap hypothesis- a hypothesis that is
based on the idea that a major earthquake
is more likely to occur along the part of an
active fault where no earthquakes have
occurred for a certain period of time
• Seismic gap- an area along a fault where
relatively few earthquakes have occurred
recently but where strong earthquakes
have occurred in the past
Lesson Summary
• Earthquake hazard is a
measure of how likely an
area is to have
earthquakes in the future.
• Seismologists use their
knowledge of the
relationship between
earthquake strength and
frequency and of the gap
hypothesis to forecast
earthquakes.
Sources
• Science textbook
• www.ask.com/images