tsunami

The Hashemite University Faculty of Natural Resources and EnvironmentEnvironmental Geology Environmental Geology Environmental Geology Environmental Geology Environmental Geology Environmental Geology

Dr . Masdouq Al-Taj

Tsunami Japanese word means harbor waves or Seismic sea wave.

AA tsunamitsunami :: is a very long-wavelength wave of water that is generated by sudden displacement of the seafloor or disruption of any body of standing water .


Dr . Masdouq Al-Taj

Tsunami Risk

Occasionally occur without warning and brings death and massive destruction to coastal communities.


Dr . Masdouq Al-Taj

Tsunami Physical Characteristics of Tsunami

1. Wave length (λ): 200 km and may reach 500 km.

2. Wave height: the distance between the trough of the wave and the crest or peak of the wave.

3. Amplitude - refers to the height of the wave

above the still water line, usually this is equal to 1/2 the wave height .


Dr . Masdouq Al-Taj

Tsunami

4. Frequency or period (P): very low frequency or have long time for one full wavelength to pass a stationary point.

5. Velocity (V) in Open Ocean reaches 950 km/hr. But when reach coastal area its velocity decreases to about 60 km/hr.

* The rate at which a wave loses its energy is inversely related to its wavelength.

Physical Characteristics of Tsunami


Dr . Masdouq Al-Taj

Tsunami

SoSo, there is a big difference between Tsunami and "tidal waves“

* * Normal Ocean waves travel with 90km/hr90km/hr .

** Wave length of normal ocean waves=100m100m.


Dr . Masdouq Al-Taj

Tsunami The influence of the shore line

Run-up: height in meters above normal high tide (it may reach 30 m near coastal areas)

How can one determine run-up?

It is varying from place to another along the coastal and the height of the wave is influenced by :

1. Depth of water (d).[ V= (g*d)1/2 ] .2. The profile of see floor.3.The shape of the coastal line.


Dr . Masdouq Al-Taj

Tsunami Water trap

The energies of the wave are concentrates on a particular site of coast line as a result of sea floor profile or the shape of the coastal line .

Bore

A wall results from the wave when concentrated in long, narrow bay or river mouth .


Dr . Masdouq Al-Taj

Tsunami Measurement of Tsunami magnitude

Imamura - Iida scale (depend on wave height at

the coast).


Dr . Masdouq Al-Taj

Tsunami How Tsunami is generated?

Any tsunami generated by Eq is called Tsunamigenic earthquakeTsunamigenic earthquake.

* Tsunami Earthquake not depends on Earthquake Magnitude but it depends on the type of movement (i.e. Strike slip, (normal or reverse= more destructive).

1. Earthquakes


Dr . Masdouq Al-Taj

Tsunami

In these setting to generate large tsunami from moderate Earthquake:

Accreting margins (Accretionary prism which cause Sediment slumping) in subduction zone.

surface rupture (plate rupture); no accreting margin .

Earthquakes


Dr . Masdouq Al-Taj

Tsunami

3. Volcanic Eruption

4. Underwater explosions

5. Tsunami in lake, bay and reservoir (Schiches)

2. Landslides


Dr . Masdouq Al-Taj

Tsunami hazards

The main damage from tsunami comes from the destructive Nature of the waves themselves.

- Primary effects


Dr . Masdouq Al-Taj

Tsunami hazards

1. Include the debris acting as projectiles which then run into other objects.

2. Erosion that can undermine the foundations of structures built along coastlines.

3. Fires that result from disruption of gas and electrical lines.

- Secondary effects


Dr . Masdouq Al-Taj

1. Loss of crops and water and electrical systems.

2. Famine and disease .

Tsunami hazards

Tertiary effects


Dr . Masdouq Al-Taj

Tsunami prediction and warning

Identifying Earthquake that is likely to generate tsunami.

Estimating the travel time a cross the ocean basin.

Prediction


Dr . Masdouq Al-Taj

Warning - Regional warning systems around the Pacific Rim have quite effective in minimizing loss of life from tsunami .

• Pacific-wide early warning system (1 hour=750 km from the source of tsunami) by The National Oceanic and Atmospheric Administration (NOAA). It gives the data to Pacific Tsunami Warning Center (PTWC). It is a system of 30 seismic station and 78 tide stations.

• Regional warning system (10 min-1 hour = 100-750 km). • Local warning system (THRUST) = (10 min = 100 km of the source).

pacific

�We ask Allah to protect us

tsunami

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