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					   Tsunami! Understanding the Generation,
    Propagation, and Hazards of Tsunamis
Larry Braile,
braile@purdue.edu,
web.ics.purdue.edu/~braile
Sheryl Braile

NSTA, Boston,
2008



                                          (Despite the popularity of
                                          this image, tsunami waves
                                          do not normally look like
                                          this.)

  This PowerPoint Presentation (last modified March 14, 2008):
  http://web.ics.purdue.edu/~braile/edumod/tsunami/Tsunami!.ppt
   Tsunamis can be generated by:
1. Large Earthquakes (megathrust events such
  as Sumatra, Dec. 26, 2004)
2. Underwater or near-surface volcanic
  eruptions (Krakatoa, 1883)
3. Comet or asteroid impacts (evidence for
  tsunami deposits from the Chicxulub impact
  65 mya)
4. Large landslides that extend into water
  (Lituya Bay, AK, 1958)
5. Large undersea landslides (evidence for
  prehistoric undersea landslides in Hawaii and
  off the east coast of North America)
       Schematic plate tectonic
    setting for tsunami generation

                TRENCH




                                NOAA
Commonly, in mega-thrust earthquakes, a very
  large area of the ocean floor is uplifted
Earthquake generation of tsunami
(note: tsunami wave in the animation should
be asymmetrical with a first peak traveling to
the right and a first trough traveling to the left)




                                        Animation




http://ffden-2.phys.uaf.edu/645fall2003_web.dir/elena_suleimani/generation_small.mov
http://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm
   Blind Thrust Fault Earthquake Rupture Animation (Northridge, 1994)
                           Brad Aagaard, USGS
 http://pasadena.wr.usgs.gov/office/baagaard/research/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.




http://web.ics.purdue.edu/~braile/new/AagaardBlindThrustAnimation.ppt
                               Exploring Planet Earth
 Blind Thrust Fault Earthquake Rupture Animation – Brad Aagaard, USGS
 http://pasadena.wr.usgs.gov/office/baagaard/research/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 seismic waves is color coded according to ground velocity.
                 Earthquake Rupture
http://pasadena.wr.usgs.gov/office/baagaard/research/animations/animations.html
Worldwide earthquakes per year (from USGS):
  Descriptor        Magnitude      Average Annually
    Great          8 and higher               1¹
    Major             7 - 7.9              17 ²
   Strong             6 - 6.9             134 ²
  Moderate            5 - 5.9            1319 ²
    Light             4 - 4.9         13,000 (est.)
    Minor             3 - 3.9        130,000 (est.)
  Very Minor          2 - 2.9        1,300,000 (est.)
        ¹ Based on observations since 1900.
        ² Based on observations since 1990.
     Worldwide earthquakes per year:




Frequency-magnitude relationship suggests that magnitude 9+
events will occur about once per decade, statistically; since
1900, the actual number is ~once per 20 years.
                  Tsunami Statistics




Tsunami Statistics (NOAA): http://wcatwc.arh.noaa.gov/tsustats.pdf
     (Dec. 26, 2004 tsunami resulted in over 200,000 deaths)




Tsunami Statistics (NOAA): http://wcatwc.arh.noaa.gov/tsustats.pdf
Tsunami wave propagation characteristics –
note that as water depth becomes smaller,
waves slow down, become shorter wavelength,
and have larger amplitude.




                NOAA
When the water is 10 m deep, what is the separation
of the waves in minutes?
   Water waves animation
         Direction of propagation




Animation courtesy of Dr. Dan Russell, Kettering University

http://www.gmi.edu/~drussell/demos.html
Tsunami velocity and amplitude equations
   (These are plane layer [flat ocean bottom] equations)

1. Wave velocity controlled by water depth:
     v = (g x d)1/2 where v is velocity, d is water
   depth and g is the acceleration of gravity = 9.8
   m/s2; so, velocity decreases in shallower water.
2. Wave height (amplitude) increases
   (conservation of energy) in shallow water:
   AS = AD x (VD/VS)1/2 where AS = amplitude in
   shallow water, AD = amplitude in deep water,
   VS = velocity in shallow water, and VD = velocity
   in deep water.
    Wave Heights – Satellite observation versus
    calculated model – open ocean, deep water




                                          ~1600 km; ~2.2 hours
                                          of waves at 750 km/hr




Geist, Titov and Synolakis, Tsunami: Wave of Change,
Scientific American, January, 2006.
Tsunami Wave Tank
1. “SnapLock Select” plastic underbed storage box
    118 x 51 x 13 cm (45” x 21” 5”) from Walmart, K-Mart, etc.
    (or Sterilite #1996, 74 qt.), remove handles, fill holes with
    silicon sealer.
2. Plexiglass
   53 x 48 x 0.5 cm
   (21” x 19” x 3/16”)
   [could use
   sand for “coastal
   area” instead of
   plexiglass].
3. Two 30 cm plastic
   rulers with clay
   base, 30 cm apart.
4. Fill to 8 cm deep
   with water.
Tsunami Wave Tank
http://www.target.com/p/Sterilite-74-qt-Ultra-Storage-Box-White/-/A-10497010
Tsunami Wave Tank (close-up of ruler and plexiglass –
note slope representing shallowing of water depth
adjacent to coast)
        Tsunami Wave Tank – Video of Wave Tank
                     Download Tank.mov from:
http://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm
            Tsunami Wave Tank – Video of Waves
Water Drop – Point source, circular spreading of energy:
 Download WaterDrop3.mov and WaterDrop4Measure.mov from:
http://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm

 1. What are the
 characteristics of the waves
 generated by the water drop?
 2. Measure the velocity of the
 wave using a stopwatch
 (distance from center to side
 of tank in cm, divided by time
 in seconds).
 3. Can you observe reflected
 waves.
 4. Why do the waves
 eventually disappear?
            Tsunami Wave Tank – Video of Waves
Line Source (plane wave) – No spreading of energy:
                   Download PlaneWave1.mov from:
 http://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm
1. What are the
characteristics of the waves
generated by the line source?
2. Measure the velocity of the
wave using a stopwatch
(follow one wave crest from first
ruler to the second – 30 cm
divided by time).
3. What is the wave height?
4. What is the wave length?
5. Do the waves get smaller
with distance of propagation?
6. What type of water wave in
the ocean is similar to these
waves?
Ocean Waves
            Tsunami Wave Tank – Video of Waves
Tsunami – Line source and entire water column disturbed:
                    Download Tsunami2.mov from:
http://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm
1. What are the characteristics
of the waves generated by the
tsunami source?
2. Measure the velocity of the
wave using single frame advance
(follow one wave crest from first
ruler to the second – 30 cm
divided by time).
3. What is the wave height?
4. What is the wave length?
5. What happens to the wave
as it propagates into shallow
water?
            Tsunami Wave Tank – Video of Waves
Tsunami – Line source and entire water column disturbed:
               Download Tsunami4Measure.mov from:
http://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm
  (Use pause and single frame advance to observe wave characteristics)
            ~5.8 s                                   ~6.2 s




 Note Long Wavelength                   Note Wave Cresting 
  Tsunami Wave Tank Materials
Wave generation sources; drop into water or oscillate up and down
   on water surface to create waves: Golf ball, plastic golf ball (or
   table tennis ball), eye dropper, clay, wood, styrofoam strips
48 x 10 x 2.5 cm
(19” x 3.75” x 1”)
26 Dec. 2004 Tsunami max. wave height and
arrival time




 Geist, Titov and Synolakis, Tsunami: Wave of Change,
 Scientific American, January, 2006.
Seismic Eruption software: http://www.geol.binghamton.edu/faculty/jones/
Indonesia area historical earthquakes files, download from:
http://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm
Seismic Eruption software: http://www.geol.binghamton.edu/faculty/jones/
Sumatra earthquake and aftershocks files, download from:
http://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm
Tsunami
simulation
(Note focusing
of energy to
west and east
of the
earthquake
rupture area)




http://staff.aist.go.jp/kenji.satake/animation.gif
Chedi Resort,
 Phuket, Thailand,
wave height ~4+ m
(?, from estimates of
water level from
beach umbrellas on
grassy area above
the beach)
Banda Aceh, Sumatra, before tsunami
http://geo-world.org/tsunami/
Banda Aceh, Sumatra, after tsunami
Also: http://www.digitalglobe.com/
Tsunami
 Resources




   Tsunami Teacher Resource Kit (17 MB pdf) from ITIC
   (International Tsunami Information Centre)
   http://www.tsunamiwave.info/
Tsunamis – Wall of Water activities
(University of Texas, Institute of Geophysics)
http://www.ig.utexas.edu/outreach/cataclysms/modules.htm
IRIS Posters: http://www.iris.edu/about/publications.htm#p
   Tsunami! Understanding the Generation,
    Propagation, and Hazards of Tsunamis
Larry Braile,
braile@purdue.edu,
web.ics.purdue.edu/~braile
Sheryl Braile

NSTA, Boston,
2008



                                          (Despite the popularity of
                                          this image, tsunami waves
                                          do not normally look like
                                          this.)

  This PowerPoint Presentation (last modified March 14, 2008):
  http://web.ics.purdue.edu/~braile/edumod/tsunami/Tsunami!.ppt

				
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