like the one that East Asia of 26
areas of South
December 2004 is made up of a special sort of sea waves. But. the tsun, crash on the coastlines of this region unleashing terror
Recognizing a TsunamiTsunamis are often referred to as tidal All Nature's vagaries are pointers of the power the violence of Nature to the overwhelming For mankind, the is an unattainable is to understand of natural disasters.
but this is influences
incorrect. as tides occur due to the gravitational superiority controlling scientific of Nature.
dream, but what is sure!>' possible basis of the occurrence turned the terror
sea into a raging monster 2004? in the bed of to northern mammoth scale, tip of
in the coastal areas of South East
Massive undersea earthquake in the bed of Indian Ocean gave birth to mammoth tsunami waves of 26 December 2004.
of the Moon, Sun, and planets. Tsunamis are not generated by the tidess. However, a tsunami that strikes a coastal area is influenced Powerful
the tide tsunamis.
at the time of impact. most ocean the normal
undersea earthQuakes or seismic activiry Unlike
(distance between the km. These plane.
crests) - often more than 100
Asia in the ear!>' hours of 26 December It was a massive Indian tsunami with region released its Ocean undersea that Measuring close Island, earthQuake birth to the
travel a deep ocean with a speed of more tsunamis are not always 'seismic sea
than 800 km per hour Le., more than the speed of a jet However, eruptions, falling Ocean. gave
as they may also be generated due to landslides, and rare!>' However, Sea and
9.0 on the Richter's this earthQuake
of a large occur in have
meteorite the Pacific
in the ocean6.
was it that it According our planet
also been generated in the Atlantic the Mediterranean
and the Indian Oceans, within smaller bodies of
made the Earth wobble on its aXis!1 The enormous energy soon circled around the globe. the scientists still initial "ringing from the Earth Sciences National Universiry, like a bell" well According Space and Research School
water, like the Sea of Marmara in Turkey.
at the Australian catastrophe.
Tectonic PlatesAccording to the Plate Tectonic Theory, the surface of the of massive rigid plates, on top of These plates change size - rough!>, the rate Earth is made up of a patchwork the Earth's hot, fleXible and position interior7.
two weeks after the to the US National (NASA). and
Aeronautics this rare seismic Pole, slightly spin
about 80 km thick, which float in slow motion
event evenaltered a little
shifted the Earth's mean North of the planet, of each day making horrifjing that it has been
the shape the length faster2 has
time, as they are constant!>' moving at a
slight!>, decreased of this
speed of about I cm to 10 cm at which fingernails ~ologic
the Earth impact
grow! As these plates
activiry occurs at the plate edges.
The surface of the farthis made up of a patchwork of massive rigid tectonic plates, about 80 km thick, which float in slowmotion on top of the farth's hot, flexible interior.These plates change size and position over time.
As some tectonic plates for new ocean noor each other without potentiallY beneath collide collision Ocean. under of
away from each other, space Some plates slide past However. in a towards each other.
causing much disturbance.
there are some plates moving dangerous
as one plate
may submerge plates
the other. As the sides of two tectonic violentlY, enormous that triggers the generation where denser oceanic continental plates.
energy is released. It is this of tsunamis. This is the margins of the Pacific plates are known to slip process is known as This
exactlY what happens around
The devastation caused on the Jndian shores by the tsunamis that hit the South East Asian coastlines recently has proved that India is too on the vulnerability chart, though chances of such an onslaught are rare.It is a horrifying tsunamis occur fact that an average of two destructive per year in the Pacific basin. although in all the oceans and inland
and the area where the chances of occurrence and earthQ!.lakes are zone8. effective
tsunamis can be generated seas of the world. About Fire extends northward the Philippines, Russia. It also
high is called the earthQuakes are
80% of all recorded earthQuakes through Fiji. Papua New Guinea, the eastern coast of
The subduction in generating
occur around the edge of the Pacific Plate. The Ring of and lapan along
Ring of FireCircling there has a the Pacific Basin, on the bottom lies a series Called of volcanic of region. the 'Ring This of the seabed. and deep and the this region called arcs of Fire', also ocean trenches. high
the region east to the southern edge Since India does not fall in of our country to the to be low. However. shores
of Alaska as well as the western coast of Canada. North
seismic belt. is home to
75% of the
It is a horrifying fad that an average of two destrudive tsunamis occur per year in the Pacific basin.
America and South America. the Ring of Fire. the devastation has proved
the vulnerability caused
experience tsunamis was considered
on the Indian
tsunamis that hit the South East Asian coastlines that India is too on the vulnerabiliry are rare. though chances of such an onslaught
As the tedonic plates collide, separate, or slide past one another, some plates gain while others lose material at their edges, which is why the plate boundaries change over geologic time.
active and dormant
Birth of the Killer WavesTsunami waves may be generated because of certain phenomena that include the following:
t han 7 .5
Undersea EarthquakesEarthQuakesusually occur in regions of the Earth along tectonic plate boundaries called faults. where different tecton ic plates meet. The chances of occurrence of earthQuakes are very high in these regions due to the collision of tectonic plates as these plates are constantly moving past each other'o. UnderstandablY. when two tectonic plates collide. a large amount of the built-up stress is released. On the other hand. intraplate earthQuakes.which are less than 10% of all earthQuakes. occur within the tectonic plates in the more stable interiors of continents. far away from plate boundaries". Although the cause of occurrence of intraplate earthQuakes is not Quite clear. these are possiblY related to the driving forces of plate tectonics. As the tectonic plates collide, separate. or slide past one another. some plates gain while others lose material at their edges. which is why the plate boundaries change over geologic time. If weakened former plate boundaries become part of the interiors of plates. stresses originating at the edges of the plates or in the deeper crust may result in intraplate earthQuakes. The most destructive tsunamis are generated by massive undersea earthQuakes.occurring at a depth shallower than 50 km with an epicentre or fault line near or on the ocean floor. Such an undersea earthQuake.of magnitude greater
on the Richter's scale. tilts and deforms large f the sea floor ranging from a few kilometers to areaS O even more than \.000 km. This sudden vertical diSplacement over large ~reas grossly di~places the seawater.which under the Influence of gravlry. tends to regain its eQ].Jilibrium.It is this vertical movement of the entire water column that generates destructive tsunami waves.As energy cannot be created or destroyed but can be only transferred from one form to another (Law of Conservation of Energy). the potential energy that results from pushing water above mean sea level is transferred to kinetic energy that initiates the horizontal propagation of the tsunami waves. If the sea floor movement is horizontal. a tsunami is usually not generated. Besides. not all undersea earthQ].Jakes create tsunamis. as it depends on the nature and degree of displacement of the seawater column. It is onlY the vertical displacement of seawater due to abrupt. jerky movement of fault blocks on the seabed that gives birth to powerful tsunamis. Once formed. the monstrous waves soon begin their journey towards the nearest coastlines. ringing the bells of doom.
Tsunamis arrive at a c