long-wavelength wave of water that is generated by sudden displacement of the seafloor or disruption of any body of standing wat

1. 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 .

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

3. 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 .

4. 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

5. 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.

6. 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.

7. 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
.

8. Tsunami
Measurement of Tsunami magnitude
Imamura - Iida scale (depend on wave height at
the coast).

9. 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

10. 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

11. Tsunami
3. Volcanic Eruption
4. Underwater explosions
5. Tsunami in lake, bay and reservoir (Schiches)
2. Landslides

12. Tsunami hazards
The main damage from tsunami comes from the
destructive Nature of the waves themselves.
- Primary effects

13. 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

14. 1. Loss of crops and water and electrical systems.
2. Famine and disease .
Tsunami hazards
Tertiary effects

15. Tsunami prediction and warning
Identifying Earthquake that is likely to generate
tsunami.
Estimating the travel time a cross the ocean
basin.
Prediction

16. 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

22. ِWe ask
Allah to protect us