Seismic%20Waves

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Making Waves Seismic Waves Activities and
Demonstrations
www.iris.edu
Sheryl Braile, Happy Hollow School West
Lafayette, IN sjbraile_at_gmail.com Larry Braile,
Purdue University braile_at_purdue.edu,
web.ics.purdue.edu/braile
CSTA Conference, October, 2017, Sacramento, CA
If you download the videos (see links on video
slides) and put them into the same folder on your
computer as this PPT (see link below), the .avi
videos embedded in the PPT will open
automatically. If you want to change the video
file type, cloudconvert.com (free) works well.
This PPT (17 MB) http//web.ics.purdue.edu/brail
e/new/SeismicWaves.ppt
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Seismic Waves

• Slinky P, S, Rayleigh, Love waves
• Reflection and transmission energy carried by
  waves elastic rebound/plate motions and the
  slinky 5-slinky model waves in all directions,
  travel times to different distances.
• Human wave demo P and S waves in solids and
  liquids.
• Seismic wave animations P, S, Rayleigh, Love
  waves wave motion wave propagation activity.
• Seismograms Viewing seismograms on your
  computer (AmaSeis software).
• Seismic Waves software Wave propagation through
  the Earth.

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Why use several approaches for teaching about
seismic waves?

• Fundamental concept (worth spending time on)
• Different approaches for different settings or
  size of group
• Different learning styles
• Reinforce with more than one approach
• Demonstrations, animations and hands-on
  activities
• Use one or more approach for authentic assessment

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Some useful seismic waves terminology Wave types
P (primary, compressional, body wave), S
(secondary, shear, body wave), Rayleigh (R,
surface wave), Love (L, surface
wave) Material properties elastic, brittle,
ductile Seis seismic, seismometer,
seismograph, seismogram, seismology,
seismologist Ground motion displacement (in cm
or m), velocity (in km/s or m/s, or cm/s for
particle velocity), acceleration (in cm/s2 or
m/s2, or g percent of the acceleration of
gravity on Earth which is 9.807 m/s2),
frequency (Hz or cycles per second),
wavelength (m or km), period (seconds or
minutes) Deformation Stress, Strain (Hookes
Law stress is proportional to strain)
strain is relative change (unit-less) in shape or
size due to applied force stress is force
per unit area associated with strain
(http//physics.bgsu.edu/stoner/p201/shm/sld002.h
tm) Seismographs mass, spring, magnet and
coil, damping, simple harmonic motion
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Seismic Wave Amplitude measured in units of
To better understand these different measures
related to motion, imagine driving your car a
short distance from a stopped position at point A
to point C, stopping at point C. Note that you
would increase your velocity and then decrease
velocity before stopping at C. The velocity
would be a maximum at about the half-way point,
B. The
A
C
B
Displacement (m)
Velocity (m/s)
Amplitude ?
Acceleration (m/s2)
or ( of g) where g 9.807 (m/s2), at surface of
Earth, acceleration due to gravity
Time ?
acceleration would be greatest between A and B,
zero at B, and the deceleration (negative
acceleration) would be greatest between B and C.
The displacement curve records the distance
traveled versus time.
For example, at a point on a fault plane during
EQ fault rupture.
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We may be most familiar with acceleration from
riding in a roller coaster. At the bottom of the
hill (below left), we feel an increased downward
force (equivalent to increased acceleration of
gravity). At the top of the hill, we may feel
weightless or even lift off the seat, being held
in the seat by the cars restraining bar.
Also http//web.ics.purdue .edu/braile/new/Accel
erometer.ppt - not on handout, large video files
The Accelerometer phone app (there are many, this
one is Accelerometer Analyzer) shows horizontal
(left-right, then up-down) acceleration, then
vertical (perpendicular to the screen)
acceleration signals. http//web.ics.purdue .edu/
braile/new/Accelerometer.avi
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Blind Thrust Fault Earthquake Rupture Animation
(Northridge, 1994) Brad Aagaard,
USGS http//pasadena.wr.usgs.gov/office/baagaard/r
esearch/animations/animations.html The fault
rupture will be visible in the animation.
Displacements (magnified 3000 times) will be
visible by the movement of the mesh from the
model. The amplitude of motions and seismic
waves is color coded according to ground
velocity. Note the rupture along the fault over
time from the deepest extent of the fault.
In the following slide (animation), we see the
displacement (exaggerated so it is visible at
this scale) in the movement of the mesh that was
used for the computer program calculations. The
color code indicates the particle velocity
amplitudes (in m/s) of the seismic waves that are
generated by the fault rupture.
http//web.ics.purdue.edu/braile/new/AagaardBlind
ThrustAnimation.ppt , Also http//web.ics.purdue
.edu/braile/edumod/tsunami/BlindThrustSlice.gif
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Blind Thrust Fault Earthquake Rupture Animation
Brad Aagaard, USGS http//pasadena.wr.usgs.gov/off
ice/baagaard/research/animations/animations.html T
he fault rupture will be visible in the
animation. Displacements (magnified 3000 times)
will be visible by the movement of the mesh from
the model. The amplitude of seismic waves is
color coded according to ground velocity.
Note that slip along the fault plane (deformation
releasing elastic energy) generates seismic waves
at every point along the fault plane that
ruptures during the earthquake, not just from a
single point (focus or hypocenter).
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Elasticity a property of materials that results
in seismic wave propagation and earthquakes (an
effective measuring activity)
Added Mass (g) Spring Extension (cm) (adding masses) Spring Extension (cm) (removing masses)
0 0.0 0.3
100 3.7 3.6
200 7.7 7.5
300 11.4 11.4
400 15.3 15.1
Difference in length of spring before and after
adding mass.
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(No Transcript)
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Click on slide to start video
Illustration of elasticity of a rock in this
case two strips of granite tile securely clamped
together at one end with a thin metal spacer
between the strips at that end (left). The
granite tile is very hard and rigid, but can be
bent, although bending too much will cause it to
break (as most rocks are brittle at low
temperatures). Note in the video, that when the
granite tile strips are squeezed together and
then released, they return to their original
position because the granite is elastic, although
much stronger (higher coefficient of elasticity)
than materials such as rubber bands, springs,
plastic, and wood that can be bent or stretched
easily. Video File http//web.ics.purdue.edu/b
raile/new/ElasticRebound.AVI
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Foam model illustrating elastic rebound concept
imagine looking down on the San Andreas fault.
Over a long period of time, the plates (Pacific
plate on left and N. American plate on right)
move at about 4 cm/yr (relative motion). View the
left and right edges of the foam as about 100 km
away from the fault. Note the deformation of the
plate, sudden slip (elastic rebound), and both
small and large ruptures (earthquakes). Video
File http//web.ics.purdue.edu/braile/new/FoamRe
bound.avi Also see http//web.ics.purdue.edu/bra
ile/edumod/foammod/foammod.htm
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How a seismometer can convert motion into an
electrical signal. Notice that the electrical
signal (voltage changes) is only generated by
movement of the magnet (with respect to the fixed
coil coated copper wire). Video File
http//web.ics.purdue.edu/braile/new/MagnetCoil.a
vi
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Geophone (with cut-out section lightweight,
portable, inexpensive seismometer). Note that
the coil moves relative to a magnet (inside the
coil) as the geophone senses motion. Geophones
similar to this one are used primarily for
seismic studies used to explore for gas and oil
in subsurface sedimentary rocks. Usually, more
sophisticated seismometers are used for
earthquake recording stations. Video File
http//web.ics.purdue.edu/braile/new/Geophone.avi
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Slinky and human wave demo and wave tank and
elasticity experiments http//web.ics.purdue.edu/
braile/edumod/slinky/slinky.htm http//web.ics.pu
rdue.edu/braile/edumod/slinky/slinky.doc http//w
eb.ics.purdue.edu/braile/edumod/slinky/slinky.pdf

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Characteristics of Seismic Waves
Table 2  Seismic Waves Table 2  Seismic Waves Table 2  Seismic Waves Table 2  Seismic Waves
Type (and names) Particle Motion Typical Velocity Other Characteristics
P,Compressional, Primary, Longitudinal Alternating compressions (pushes) and dilations (pulls) which are directed in the same direction as the wave is propagating (along the raypath) and therefore, perpendicular to the wavefront VP 5 7 km/s in typical Earths crust     gt 8 km/s in Earths mantle and core  1.5 km/s in water 0.3 km/s in air P motion travels fastest in materials, so the P-wave is the first-arriving energy on a seismogram.  Generally smaller and higher frequency than the S and Surface-waves.  P waves in a liquid or gas are pressure waves, including sound waves.
S,   Shear, Secondary, Transverse Alternating transverse motions (perpendicular to the direction of propagation, and the raypath) commonly polarized such that particle motion is in vertical or horizontal planes VS 3 4 km/s in typical Earths crust     gt 4.5 km/s in Earths mantle    2.5-3.0 km/s in (solid) inner core S-waves do not travel through fluids, so do not exist in Earths outer core (inferred to be primarily liquid iron) or in air or water or molten rock (magma).  S waves travel slower than P waves in a solid and, therefore, arrive after the P wave.
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Characteristics of Seismic Waves
L,  Love, Surface waves, Long waves Transverse horizontal motion, perpendicular to the direction of propagation and generally parallel to the Earths surface VL   2.0 - 4.5 km/s in the Earth depending on frequency of the propagating wave Love waves exist because of the Earths surface.  They are largest at the surface and decrease in amplitude with depth.  Love waves are dispersive, that is, the wave velocity is dependent on frequency, with low frequencies normally propagating at higher velocity.  Depth of penetration of the Love waves is also dependent on frequency, with lower frequencies penetrating to greater depth.
R,   Rayleigh, Surface waves, Long waves, Ground roll Motion is both in the direction of propagation and perpendicular (in a vertical plane), and  phased so that the motion is generally elliptical either prograde or retrograde VR   2.0 - 4.5 km/s in the Earth depending on frequency of the propagating wave Rayleigh waves are also dispersive and the amplitudes generally decrease with depth in the Earth.  Appearance and particle motion are similar to water waves.
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A simple wave tank experiment a ping pong ball
is dropped onto the surface of the water small
floats aid viewing of the wave energy. Distance
marks on the bottom of the container allow
calculation of wave velocity. A stopwatch can be
used to time the wave travel time to each
distance and calculate wave velocity. Repeat
measurements can improve accuracy and allow
estimation of measurement error. Slow motion
video can also be used to improve time
measurements. You can also video with phone or
camera.
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Seismic waves and the slinky (also, see the
4-page slinky write-up at http//web.ics.purdue.e
du/braile/edumod/slinky/slinky4.doc)

• P and S waves
• Love and Rayleigh waves
• Wave reflection and transmission
• Elastic rebound
• Waves carry energy
• The five slinky model (waves in
• all directions and different travel
• times to different locations the
• way that earthquakes are located)

Seismic waves carry energy. Observe the shaking
of the model building when P and S waves are
propagated along the slinky.
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The 5-slinky model for demonstrating that seismic
waves propagate in all directions and the
variation of travel time with distance. It can
also be used to illustrate the method that
seismologists use to locate earthquakes (x, y, z,
and origin time), mostly from many P-wave arrival
times.
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Triangulation example for locating the position
of a lightning strike. The lightning to thunder
delay time is used to determine distance and aids
in lightning safety. This example is similar to
the S minus P method of earthquake location.
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The human wave demonstration illustrating P and
S wave propagation in solids and liquids.
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The people wave (Dan Russell)
Wave animations
Rayleigh wave propagation
Seismic Wave animations (L. Braile) http//web.ics
.purdue.edu/braile/edumod/waves/WaveDemo.htm

Courtesy of Dr. Dan Russell, Penn State
University

• Courtesy of Dan Russell, Penn St. Univ.
  http//www.acs.psu.edu/drussell/

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Four Types of Seismic Waves
(http//web.ics.purdue.edu/braile
/new/SeismicWaves4Types.ppt)
Deformation propagates. Particle motion consists
of alternating compression and dilation.
Particle motion is parallel to the direction of
propagation (longitudinal). Material returns to
its original shape after wave passes.
Deformation propagates. Particle motion consists
of alternating transverse motion, perpendicular
to direction of propagation. Transverse motion
can be in any direction. Material returns to its
original shape after wave passes.
Deformation propagates. Particle motion consists
of alternating transverse motions. Particle
motion is horizontal and perpendicular to the
direction of propagation (transverse). Amplitude
decreases with depth. Material returns to its
original shape after wave passes.
Deformation propagates. Particle motion consists
of elliptical motions (generally retrograde
elliptical) in the vertical plane and parallel to
the direction of propagation. Amplitude
decreases with depth. Material returns to its
original shape after wave passes.
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Compressional Wave (P-Wave) Animation
Deformation propagates. Particle motion consists
of alternating compression and dilation.
Particle motion is parallel to the direction of
propagation (longitudinal). Material returns to
its original shape after wave passes.
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Shear Wave (S-Wave) Animation
Deformation propagates. Particle motion consists
of alternating transverse motion. Particle
motion is perpendicular to the direction of
propagation (transverse). Transverse particle
motion shown here is vertical but can be in any
direction. However, Earths layers tend to cause
mostly vertical (SV in the vertical plane) or
horizontal (SH) shear motions. Material returns
to its original shape after wave passes.
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Rayleigh Wave (R-Wave) Animation
Deformation propagates. Particle motion consists
of elliptical motions (generally retrograde
elliptical) in the vertical plane and parallel to
the direction of propagation. Amplitude
decreases with depth. Material returns to its
original shape after wave passes.
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Love Wave (L-Wave) Animation
Deformation propagates. Particle motion consists
of alternating transverse motions. Particle
motion is horizontal and perpendicular to the
direction of propagation (transverse). To aid in
seeing that the particle motion is purely
horizontal, focus on the Y axis (red line) as the
wave propagates through it. Amplitude decreases
with depth. Material returns to its original
shape after wave passes.
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You can download the animations separately to run
more efficiently http//web.ics.purdue.edu/brail
e/edumod/waves/WaveDemo.htm A complete
PowerPoint presentation on the Seismic wave
animations is also available at
http//web.ics.purdue.edu/braile/edumod/waves/Wav
eDemo.ppt

• Demonstrate the AmaSeis software for displaying
  and analyzing seismograms software available at
  http//bingweb.binghamton.edu/ajones/
• A tutorial on AmaSeis and links to seismograms
  that can be downloaded and viewed in AmaSeis
  available at
• http//web.ics.purdue.edu/braile/edumod/as1lesson
  s/UsingAmaSeis/UsingAmaSeis.htm
• IRIS Seismographs in Schools program
  http//www.iris.edu/hq/sis
• IRIS Wave Visualizations
• http//www.iris.edu/hq/programs/education_and_outr
  each/visualizations
• USGS/SCEC SAF EQ Simulations
• http//earthquake.usgs.gov/regional/nca/simulation
  s/shakeout/
• Quake Catcher Network MEMS accelerometers
  http//quakecatcher.net/
• Graphical earthquake location method illustrating
  locations using p-wave arrival times (similar to
  the optimization method used by seismologists)
  http//web.ics.purdue.edu/braile/edumod/eqlocate/
  tutorial.htm
• S-P earthquake location tutorial
  http//web.ics.purdue.edu/braile/edumod/as1lesson
  s/EQlocation/EQlocation.htm

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(software developed by Alan Jones, SUNY
Binghamton, NY)
IRIS Seismographs in Schools program
http//www.iris.edu/hq/sis
24-Hour Screen Display
Extracted Seismogram
The AS-1 Seismometer
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Teaching Modules and Tutorials for educational
seismographs http//web.ics.purdue.edu/braile/ed
umod/as1lessons/as1lessons.htm (in module 13,
you can download real seismic data from past
years and use with the AmaSeis program on your
computer even if you do not have a
seismograph) IRIS educational seismographs web
page http//www.iris.edu/hq/sis/resources/seismom
eters The AS-1 is a portable effective classroom
tool for teaching about earthquakes and the
instruments that record them. The AS-1 has been
loaned to many teachers through the Seismographs
in Schools program. The AS-1 electronics have
recently been redesigned and production is
currently underway! EQ-1 Seismograph
http//wardsci.com/product.asp_Q_pn_E_IG0018602_A_
VerticalSchoolSeismometer TC-1 Slinky
Seismograph http//cgiss.boisestate.edu/bsu-netwo
rk/ http//cgiss.boisestate.edu/construction-of-th
e-tc1/ http//tc1seismometer.wordpress.com/
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Infiltec Seismometers QM-4.5LV Seismometer
long period seismometer for earthquake
monitoring. QM-4.5V-20HZ Seismometer
High-frequency seismometer for illustrating
shaking from local disturbance (stomp test). Can
order from Amazon, Ebay, or Infiltec (540)
943-2776 345
Stream View- jAmaSeis helicorder screen now has
the flexibility to display up to three streams of
data simultaneously. These can include a local
educational seismometer, a remote educational
seismometer over the jAmaSeis network (in true
real-time), or research-quality seismometers
stored at the IRIS Data Management Center (in
near real-time). IRIS Seismographs in Schools
information http//www.iris.edu/hq/sis.
http//www.iris.edu/hq/programs/education_and_outr
each/software/jamaseis
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The Seismic Waves program

• From Alan Jones, SUNY, Binghamton
• http//bingweb.binghamton.edu/ajones/

Earthquake

Wavefront
Cross Section Through Earth
Ray Path
Stations for Seismograms
Seismograph
Ray Path is perpendicular to wavefront
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Time T1
Earthquake

Wavefront
Cross Section Through Earth
Ray Path
Stations for Seismograms
Seismograph
Ray Path is perpendicular to wavefront
Time T2
Earthquake

Wavefront
Cross Section Through Earth
Ray Path
Stations for Seismograms
Seismograph
Ray Path is perpendicular to wavefront
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Earths interior structure and seismic raypaths
that are used to determine the Earth structure.
http//www.iris.edu/hq/files/programs/education_an
d_outreach/lessons_and_resources/images/ExplorEart
hPoster.jpg
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? Alan Jones Seismic Eruption (SeisVolE) program
(Windows), 1987 Loma Prieta earthquake.
https//www.binghamton.edu/geology/people/faculty/
jones.html
Earthquake plotting and analysis software
June-September, 2017 ? earthquakes in
southern Mexico viewed with the IRIS IEB (IRIS
Earthquake Browser, http//ds.iris.edu/ieb/)
web-based earthquake plotting site. (IEB
tutorial and lab activity http//web.ics.purdue.e
du/braile/new/LI9.doc and
http//web.ics.purdue.edu/braile/new/LR9.doc)
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Making Waves Seismic Waves Activities and
Demonstrations
www.iris.edu
Sheryl Braile, Happy Hollow School West
Lafayette, IN sjbraile_at_gmail.com Larry Braile,
Purdue University braile_at_purdue.edu,
web.ics.purdue.edu/braile
CSTA Conference, October, 2017, Sacramento, CA
PowerPoint file http//web.ics.purdue.edu/brail
e/new/SeismicWaves.ppt (17 MB)