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.)

Tsunami! Understanding the Generation, Propagation, and

Hazards of Tsunamis

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

NOAACommonly, in mega-thrust earthquakes, a

very large area of the ocean floor is uplifted

TRENCH

Earthquake generation of tsunami(note: tsunami wave in the animation shouldbe asymmetrical with a first peak traveling to the right and a first trough traveling to the left)

http://ffden-2.phys.uaf.edu/645fall2003_web.dir/elena_suleimani/generation_small.movhttp://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm

Animation

Exploring Planet Earth

Blind Thrust Fault Earthquake Rupture Animation (Northridge, 1994)Brad Aagaard, USGS

http://pasadena.wr.usgs.gov/office/baagaard/research/animations/animations.htmlThe 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

Blind Thrust Fault Earthquake Rupture Animation – Brad Aagaard, USGS

http://pasadena.wr.usgs.gov/office/baagaard/research/animations/animations.htmlThe 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.

http://pasadena.wr.usgs.gov/office/baagaard/research/animations/animations.html

Earthquake Rupture

Descriptor Magnitude Average Annually

Great 8 and higher 1 ¹

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 (from USGS):

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 (NOAA): http://wcatwc.arh.noaa.gov/tsustats.pdf

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

Tsunami Statistics

Tsunami wave propagation characteristics – note that as water depth becomes smaller, waves slow down, become shorter wavelength, and have larger amplitude.

When the water is 10 m deep, what is the separation of the waves in minutes?

NOAA

Animation courtesy of Dr. Dan Russell, Kettering University

http://www.gmi.edu/~drussell/demos.html

Water waves animation

Direction of propagation

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.

Geist, Titov and Synolakis, Tsunami: Wave of Change, Scientific American, January, 2006.

Wave Heights – Satellite observation versus calculated model – open ocean, deep water

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

Tsunami Wave Tank1. “SnapLock Select” plastic underbed storage box 118 x 51 x 13 cm (45” x 21” 5”) from Walmart, K-Mart, etc. (or Sterilite #1996), 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

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 TankDownload 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 wavesgenerated 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 timein seconds).3. Can you observe reflectedwaves.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 wavesgenerated by the line source?2. Measure the velocity of the wave using a stopwatch (follow one wave crest from firstruler 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 smallerwith distance of propagation?6. What type of water wave inthe ocean is similar to thesewaves?

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 firstruler 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”)

Geist, Titov and Synolakis, Tsunami: Wave of Change, Scientific American, January, 2006.

26 Dec. 2004 Tsunami max. wave height and arrival time

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 tsunamihttp://geo-world.org/tsunami/

Banda Aceh, Sumatra, after tsunamiAlso: http://www.digitalglobe.com/

Tsunami Teacher Resource Kit (17 MB pdf) from ITIC (International Tsunami Information Centre) http://www.tsunamiwave.info/

Tsunami Resources

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

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.)

Tsunami! Understanding the Generation, Propagation, and

Hazards of Tsunamis

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