arry Braile, [email protected], b.ics.purdue.edu/~braile heryl Braile STA/NSTA, Long Beach, A, December 4-6, 2014 (Despite the popularity of this image, tsunami waves do not normally look like this, especially in the open ocean) Tsunami! Understanding the Generation, Propagation, and Hazards of Tsunamis This PowerPoint Presentation (last modified December, 2014): http://web.ics.purdue.edu/~braile/edumod/tsunami/Ts
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Larry Braile, [email protected], web.ics.purdue.edu/~braile Sheryl Braile CSTA/NSTA, Long Beach, CA, December 4-6, 2014 (Despite the popularity of this.
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Tsunamis can be generated by:1. Large Earthquakes (megathrust events
such as Sumatra, Dec. 26, 2004; Japan, Mar. 11, 2011)
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 left and a first trough traveling to the right)
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://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.
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 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? (hint: t = v)
NOAA
Animation courtesy of Dr. Dan Russell, Kettering University
(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, 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 TankDownload Tank.mov from:
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?
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?
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?
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
Tsunami simulation(Note: wave trough is first arriving energy propagating to the East, and focusing of energy to west and east of the earthquake rupture area)
Chedi Resort,Phuket, Thailand, wave height ~4+ m (?, from estimates of water level from beach umbrellas on grassy area above the beach)
Tilly Smith and the Dec. 26, 2004 Sumatra tsunami, Phuket, Thailand (about 10,000 people were killed by the tsunami in Thailand; Tilly is credited with saving the lives of about 100 people because she recognized the warning signs of an oncoming tsunami.
“Tilly Smith learned about tsunamis in a geography lesson two weeks before the tsunami from her teacher Andrew Kearney at Danes Hill School in Oxshott, Surrey. She recognised the symptoms of receding water from the shoreline and frothing bubbles on the surface of the sea and alerted her parents, who warned others on the beach and the staff at the hotel on Phuket, where they were staying. The beach was evacuated before the tsunami reached shore, and was one of the few beaches on the island with no reported casualties.” (http://en.wikipedia.org/wiki/Tilly_Smith)
Banda Aceh, Sumatra, before tsunamihttp://geo-world.org/tsunami/
Up to 10 m high tsunami waves hit coastal area near Up to 10 m high tsunami waves hit coastal area near Sendai, in northern Honshu, JapanSendai, in northern Honshu, Japan
Tohoku, Japan tsunami, March 11, 2011
Tohoku, Japan Earthquake: Aftershock (and Foreshock) Sequence, 03/08/11 - 03/16/11
Note that the magnitudes of the 2011/03/11 06:15 (Mw 7.9) and 2011/03/11 06:25 (Mw 7.7) aftershocks were updated from earlier, lower estimates. Updates occurred on 03/16 and 03/18, respectively.
Kahului, Maui Tide data, March 8 – March 10, 2011 GMT
Tsunami Damage from the Tohoku [Northern Honshu, Japan] M9.0 Earthquake of March 11 – Satellite View before Tsunamihttp://www.nytimes.com/interactive/2011/03/13/world/asia/satellite-photos-japan-before-and-after-tsunami.html
Tsunami Damage from the Tohoku [Northern Honshu, Japan] M9.0 Earthquake of March 11 – Satellite View after Tsunamihttp://www.nytimes.com/interactive/2011/03/13/world/asia/satellite-photos-japan-before-and-after-tsunami.html
Tsunami Damage from the Tohoku [Northern Honshu, Japan] M9.0 Earthquake of March 11 – Satellite View before Tsunamihttp://www.nytimes.com/interactive/2011/03/13/world/asia/satellite-photos-japan-before-and-after-tsunami.html
Tsunami Damage from the Tohoku [Northern Honshu, Japan] M9.0 Earthquake of March 11 – Satellite View after Tsunamihttp://www.nytimes.com/interactive/2011/03/13/world/asia/satellite-photos-japan-before-and-after-tsunami.html
Some other recent tsunamis that have impacted the western U.S.
1946 Aleutian Islands earthquake (M8.6)
Tsunami wave heights and fatalities: Oregon and California – Coo’s Bay (~3 m), Ft. Bragg (~2-3 m), Half Moon Bay (~3-4 m), Muir Beach (~4 m), Santa Cruz (~3 m, one death). Hawaiian Islands – (6-7 waves, ~15 minute period, ~8-16 m, 159 deaths, mostly in Hilo).
1964 Aleutian Islands earthquake (M9.2)
Tsunami wave heights and fatalities: Seaside, Oregon (3-4 m, 4 deaths, Crescent City, California (6 m), 12 deaths in California.
“A simulated tsunami reaches Japan ten hours after its start along the Pacific coast of North America” (http://pubs.usgs.gov/pp/pp1707).
http://pubs.usgs.gov/pp/pp1707/pp1707.pdf
Tsunami simulation for megathrust earthquake in Cascadia impacting Japan, and other locations on the Pacific ocean basin (http://pubs.usgs.gov/pp/pp1707).
Earthquake and Tsunami Safety• Earthquake safety – “Duck and cover”.
• Tsunami safety (when in a coastal, near-sea-level area; two situations: local EQ or distant EQ):
• If you feel strong shaking for 15+ seconds; after shaking, move to higher ground.
• If there is a tsunami warning, or if you observe unusual waves (appear to be large and rapid tidal changes, or water recedes), move to higher ground.
• Do not return until event is over; a tsunami includes multiple waves sometimes separated
by 10-30 minutes and may last for hours.
Tsunami Teacher Resource Kit (17 MB pdf) from ITIC (International Tsunami Information Centre) http://www.tsunamiwave.info/