Download EARTHQUAKES

EARTHQUAKES
cont’d …. September 19
and 20th
8.E.5B.3
FALCON FOCUS
THE POINT ON EARTH’S SURFACE WHERE THE
GREATEST ENERGY FROM THE EARTHQUAKE IS
RELEASED IS ___________.
A.
THE EPICENTER
B.
THE FOCUS
C.
THE ASTHENOSPHERE
D.
THE FAULT
ESSENTIAL QUESTION
 HOW WOULD YOU COMPARE AND CONTRAST
THE THREE TYPES OF SEISMIC WAVES?
Performance Indicator
 8.E.5B.1 Analyze and interpret
data to describe patterns in the
location of volcanoes and
earthquakes related to tectonic
plate boundaries, interactions,
and hot spots
Review
 Scientists study and record seismic data and
volcanic activity in order to support the theory of
plate tectonics. The evidence proves that there is a
distinct relationship between seismic activity,
volcanic activity, and the lithospheric plate
boundaries.
 Seismic Data and Plate Tectonics: The interaction
along plate boundaries results in an increased
frequency (occurrence) of earthquakes at those
locations. Additionally, stronger earthquakes are
more likely to occur along active plate boundaries.
Strong earthquakes are more common at transform
and convergent plate boundaries. The San Andreas
fault in California is an example of an active
transform plate boundary.
Earthquakes are measured using the Richter
Scale. The strongest earthquake ever
measured was a 9.5 on the Richter Scale. This
is a measurement of the amount of energy
released from the earthquake.
How are Earthquakes Measured?
Richter Scale
Focus and Epicenter of Earthquake
SEISMIC WAVES
 _SEISMIC WAVES___ are waves generated by an
earthquake that travel through the Earth. These waves
can cause the ground to move forward, backward, up,
down, and even to ripple. Seismic Waves are generated
at the __SAME___ time but move in different ways, and
at different speeds.
Seismic
Waves in
the Earth
http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM
3 TYPES OF SEISMIC WAVES
 PRIMARY (P) WAVES
 SECONDARY (S) WAVES
 SURFACE WAVES
Seismic Waves
PRIMARY (P) WAVE
 Position: The first seismic wave to Move out from the
earthquake focus, the point where the energy is released
 Travel the fastest of the three waves
 Movement: Push and pull rock creating a back-and-forth
motion in the direction the wave is moving… this is known as
a (longitudinal wave)
 A type of seismic wave that compresses and expands
the ground
PRIMARY (P) WAVE
Moves through what states
of matter: Moves through
solid and liquid layers of Earth
(it also can move in gas)
Primary Waves (P Waves)
 A type of seismic wave that compresses
and expands the ground
 The first wave to arrive at an earthquake
http://daphne.meccahosting.com/~a0000e89/insideearth2.htm
Secondary Waves (S
Waves)
 Position: The 2nd wave to Move out from the
earthquake focus
 Move slower than primary waves
 Movement: Move at right angles to primary waves
causing rocks to move up and down and side to side …
this is known as a (transverse wave)
 A type of seismic wave that moves the ground up
and down or side to side
Secondary Waves (S
Waves)
 Moves through what states of matter :
 Can only move through solid rock
 Question: If S-waves can only move through solids,
then which EARTH layer can’t it go through?
OUTER CORE!!!!
Seismic Waves Paths Through the Earth
Earth’s Interior Showing
P and S Wave Paths
Secondary Waves (S
Waves)
 A type of seismic wave that moves the ground up and
down or side to side
http://daphne.meccahosting.com/~a0000e89/insideearth2.htm
HOW WOULD YOU
COMPARE AND
CONTRAST
PRIMARY &
SECONDARY
WAVES?
Comparing Seismic Waves
Seismic Waves Activity:
Illustrate & explain the
seismic waves based on
the Pop & Lock Activity.
ACTIVITY
 CREATE S, P, AND SURFACE WAVES USING A
STRING AND A SLINKY
Primary or
“P” Wave
Secondary
or “S”
Wave
SURFACE WAVES
 POSITION: Form when P and S waves reach
the surface AND THESE WAVES ARE
CONSIDERED THE MOST DESTRUCTIVE
SEISMIC WAVES.
 Especially damaging to buildings
 MOVEMENT: Can cause the ground to shake
making rock sway from side to side and roll like an
ocean wave
 Travel just below or along the ground’s surface

 Produces motion in the upper crust
 Motion can be up and down
 Motion can be around
 Motion can be back and forth
 (Mainly moves like P & S waves)
Moves through what
states of matter
Moves through all the
states of matter: solid,
liquid, and gas
Surface Waves
 Scientists use the principle that the speed and
direction of a seismic wave depends on the
material it travels through. Because of the
behavior of these different waves, scientists have
indirect evidence for the solid inner core and
liquid outer core of Earth; because earthquake
waves travel faster through the mantle than
through the crust, scientists know that the mantle
is denser than the crust.
Earthquake Waves & Earth’s Interior
Measuring Earthquakes
 The energy spreads outward in all directions as
vibrations called ___Seismic Waves____. Seismic
waves can be measured and recorded by a
____seismograph_______.
 __Seismographs______ are instruments or a
device that detects and records seismic or
earthquake waves. It measures the vertical ground
motion and the horizontal ground motions (N-S/EW). It also traces wave shapes onto paper and
translates waves into an electronic signal.
Measuring Earthquakes
 The vibration record, called a seismogram,
looks like jagged lines on paper.
Seismograms are traces of amplified,
electronically recorded ground motion made
by seismographs.
 Measuring the time between the arrival of
the P and S waves determines the distance
between the recording seismograph and the
earthquake epicenter.
Measuring Earthquakes
SEISMOGRAPH
SEISMOGRAM
Seismograph
Types of Seismographs
Seismogram Printout
Seismic wave behavior

P waves arrive first, then S waves, then L and R

Average speeds for all these waves is known

After an earthquake, the difference in arrival times at a seismograph station can be used to calculate the distance from the seismograph to the epicenter.
How is an Earthquake’s Epicenter Located?
LOCATING AN EARTHQUAKES
EPICENTER
 TRIANGULATION identifies the epicenter of an
earthquake. The location of an earthquake’s epicenter is
found by plotting 3 circles on a map from the records of
three seismograph stations and finding the point where the
three circles intersect. Three seismograph stations are
needed to locate the epicenter of an earthquake.
Locating an Earthquake
EPICENTER
How is an Earthquake’s
Epicenter Located?

Three seismograph stations
are needed to locate the
epicenter of an earthquake

The intersection of the
circles locates the epicenter
Locating an Earthquake Epicenter
 Triangulate means to use three positions to
determine an exact location.
Locating Earthquakes
http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM
Locating Earthquakes
http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM
Locating Earthquakes
http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM
Triangulation
of 3 stations
to locate
earthquake
epicenter
How do scientists calculate how far a location is
from the epicenter of an earthquake?
CALCULATING THE S-P INTERVAL:
 Scientists calculate the difference
between arrival times of the P waves and
S waves
 The further away an earthquake is, the
greater the time between the arrival of
the P waves and the S waves
Earthquake Waves (Review)
 Primary Wave (P-Wave)
First set of waves
 Move side to side
 FASTEST wave
 Secondary Wave (S-Wave) Second set of waves
 Move up and down
 Travel slow
 Surface Wave
 Move up and down & side to side
 MOST DANGEROUS
 SLOWEST Wave
Closure
 Create a Venn Diagram contrasting and comparing the 2
types of seismic waves.
Homework
 Study for Quiz
 Place the following words in your glossary.
 Primary wave, Secondary wave, Surfaces wave,
Longitudinal wave, Transverse wave, Richter Scale,
Seismograph, Seismogram, Magnitude, and Intensity.