TsunamisTsunamisBy Philip StubbsBy Philip Stubbs

What is a Tsunami?What is a Tsunami?

Japanese Meaning: Tsu = Harbor Nami = WaveJapanese Meaning: Tsu = Harbor Nami = Wave

Tsunamis= sequences of waves (wave train) that form in body of water.Tsunamis= sequences of waves (wave train) that form in body of water.

Water is displaced by things like earthquakes, landslides, and volcanoes.Water is displaced by things like earthquakes, landslides, and volcanoes.

Attack coastlines making them real dangerous when they hit land=altering Attack coastlines making them real dangerous when they hit land=altering landscapes and killing thousands of people.landscapes and killing thousands of people.

Referred to tidal waves at time, but are not caused by winds.Referred to tidal waves at time, but are not caused by winds.

Seismic WavesSeismic Waves

Characteristics of Tsunami Waves in Deep WaterCharacteristics of Tsunami Waves in Deep Water

Have characteristics of shallow-water waves in deep water. The ratio Have characteristics of shallow-water waves in deep water. The ratio between water depth and wavelength is really small.between water depth and wavelength is really small. Long periods and long wavelengths.Long periods and long wavelengths.Regular waves= wavelengths of 150m and periods of 10sRegular waves= wavelengths of 150m and periods of 10sTsunami waves=wavelengths over 100 km and periods longer than one Tsunami waves=wavelengths over 100 km and periods longer than one hour. hour. Because of their small heights and long wavelengths, they can go unnoticed Because of their small heights and long wavelengths, they can go unnoticed deep at sea.deep at sea.Combo of transverse and longitudinal motion=circular motionCombo of transverse and longitudinal motion=circular motionSpeed= square root of the product of acceleration of gravity (9.8 m/s/s) and Speed= square root of the product of acceleration of gravity (9.8 m/s/s) and water depth.water depth.If the water depth is 4000 m, the tsunami travels at a speed of about 200 If the water depth is 4000 m, the tsunami travels at a speed of about 200 m/s.m/s.In the deepest oceans, the waves can exceed 600 miles per hour.In the deepest oceans, the waves can exceed 600 miles per hour.Tsunamis can cross over the Pacific in less than 24 hours.Tsunamis can cross over the Pacific in less than 24 hours.

Tsunami coming towards LandTsunami coming towards Land

A transformation occurs when a tsunami goes into shallow water.A transformation occurs when a tsunami goes into shallow water.Since water depth is a factor in speed, a tsunami decreases in speed.Since water depth is a factor in speed, a tsunami decreases in speed.Since the speed decreases, the tsunami’s height will be taller (conservation Since the speed decreases, the tsunami’s height will be taller (conservation of energy).of energy).Top of waves travel quicker than bottom halfTop of waves travel quicker than bottom half Very little energy lost because the wavelength does not decrease much.Very little energy lost because the wavelength does not decrease much.When a tsunami hits land, it appears as a sequence of breaking waves.When a tsunami hits land, it appears as a sequence of breaking waves.

Tsunami approaching LandTsunami approaching Land

Tsunami on LandTsunami on LandAs soon as tsunamis enter land, they lose energy. The rate that they lose As soon as tsunamis enter land, they lose energy. The rate that they lose energy is inversely related to the wavelength. Wavelength decreases=loss energy is inversely related to the wavelength. Wavelength decreases=loss of energyof energy

Some of the energy is lost due to friction and turbulence.Some of the energy is lost due to friction and turbulence.

As well as wavelength, period decreases alsoAs well as wavelength, period decreases also

Since wavelength decreases, frequency increasesSince wavelength decreases, frequency increases

Can reach heights up to 30 meters and even higher.Can reach heights up to 30 meters and even higher.

Run-up height= max vertical height onshore Run-up height= max vertical height onshore

The waves eventually break and flood land.The waves eventually break and flood land.

Areas within 200 meters of coast most at riskAreas within 200 meters of coast most at risk

TsunamisTsunamis

No advance warning of approaching tsunamiNo advance warning of approaching tsunami

Good indicator: earthquake near body of waterGood indicator: earthquake near body of water

Good indicator: dramatic water level dropGood indicator: dramatic water level drop

80% of all tsunamis take place in Pacific Ocean80% of all tsunamis take place in Pacific Ocean

Hard to Predict and PreventHard to Predict and Prevent

Mainly take place in Asia-Pacific regionMainly take place in Asia-Pacific region

Very Common in JapanVery Common in Japan

The top picture shows Sri Lanka in 2004 when the tsunami hit SE Asia. (flooding and violent waves)

The bottom picture shows Sri Lanka in 2004 a year before the tsunami hit SE Asia. (calm, harmless waves)

BibliographyBibliography

• "ABC News: Fast Facts on Tsunamis." "ABC News: Fast Facts on Tsunamis." ABC News: Online news, breaking news, feature ABC News: Online news, breaking news, feature stories and morestories and more. 28 Dec. 2004. 06 Jan. 2009 . 28 Dec. 2004. 06 Jan. 2009 <http://abcnews.go.com/Technology/Weather/story?id=365979>.<http://abcnews.go.com/Technology/Weather/story?id=365979>.

• Newman, David. "The Physics of Tsunamis." Newman, David. "The Physics of Tsunamis." David Newman's PageDavid Newman's Page. 2005. 06 Jan. 2009 . 2005. 06 Jan. 2009 <http://ffden2.phys.uaf.edu/212_spring2005.web.dir/Justin_Priest/Tsunami%20Physics.htm>.<http://ffden2.phys.uaf.edu/212_spring2005.web.dir/Justin_Priest/Tsunami%20Physics.htm>.

• "Physics of Tsunamis." "Physics of Tsunamis." Earth and Space Sciences (Geology and Geophysics) at UWEarth and Space Sciences (Geology and Geophysics) at UW. 23 Mar. . 23 Mar. 2005. 06 Jan. 2009 2005. 06 Jan. 2009 <http://www.geophys.washington.edu/tsunami/general/physics/physics.html>.<http://www.geophys.washington.edu/tsunami/general/physics/physics.html>.

• Uy, Anthony. "The Physics of Tsunamis: The Harbor Wave." Uy, Anthony. "The Physics of Tsunamis: The Harbor Wave." UBC PhysAstro: Home PageUBC PhysAstro: Home Page. . 2006. 06 Jan. 2009 <http://www.physics.ubc.ca/~outreach/phys420/p420_05/anthony/The2006. 06 Jan. 2009 <http://www.physics.ubc.ca/~outreach/phys420/p420_05/anthony/The%20Physics%20of%20Tsunamis.htm>.%20Physics%20of%20Tsunamis.htm>.