(b) Read the passage carefully and answer the following questions:
Tsunami or the Harbour wave struck havoc in the Indian Ocean on the
26th of December 2004. The wave was the result of an earthquake that
had its epicentre near the western boundary of Sumatra. The magnitude
of the earthquake was 9.0 on the Richter scale. Indian plate went under
the Burma plate, there was a sudden movement of the sea floor, causing
the earthquake. The ocean floor was displaced by about 10 – 20m and
tilted in a downward direction. A huge mass of ocean water flowed to fill in
the gap that was being created by the displacement. This marked the
withdrawal of the water mass from the coastlines of the landmasses in the
south and Southeast Asia. After thrusting of the Indian plate below the
Burma plate, the water mass rushed back towards the coastline as a
tsunami. Tsunami travelled at a speed of about 800 km. per hour,
comparable to speed of commercial aircraft and completely washed away
some of the islands in the Indian ocean. The Indira point in the Andaman
and Nicobar Islands that marked the southernmost point of India got
completely submerged. As the wave moved from earthquake epicentre
from Sumatra towards the Andaman Islands and Sri Lanka,
the wavelength decreased with decreasing depth of water. The travel
speed also declined from 700-900 km per hour to less than 70 km per
hour. Tsunami waves travelled up to a depth of 3 km from the coast killing
more than 10,000 people and affected more than lakh of houses. In India,
the worst affected were the coastal areas of Andhra Pradesh, Tamil Nadu,
Kerala, Pondicherry and the Andaman and Nicobar Islands.
(i) What was the cause of Tsunami which was occurred in 26th Dec.2004
in Indian Ocean?
(ii) Which Southernmost point was completely submerged?
(iii) Tsunami travelled at a speed of about _______.
(iv) Name the place where the early warning system which predict in
advance?
(v) Where was its epicenter?
Answers
Answer:
Explanation:
1)A powerful undersea earthquake that struck off the coast of Sumatra island, Indonesia, set off the 2004 Indian Ocean tsunami, also known as the Christmas or Boxing Day tsunami, on Sunday morning, Dec. 26, 2004. ... The quake caused the ocean floor to suddenly rise by as much as 40 meters, triggering a massive tsunami.
2)Indira point
Tsunami travelled at a speed of about 800km. per hour, comparable to speed of commercial aircraft and completely washed away some of the islands in the Indian ocean. The Indira point in the Andaman and Nicobar islands that marked the southernmost point of India got completely submerged.
3)In the deep ocean, the typical water depth is around 4000 m, so a tsunami will therefore travel at around 200 m/s, or more than 700 km/h. For tsunamis that are generated by underwater earthquakes, the amplitude of the tsunami is determined by the amount by which the sea-floor is displaced.
4)Early warning systems have been developed and implemented for: Geological hazards like tsunamis, earthquakes, volcanic activity, and landslides. Hydrometeorological hazards including severe weather in land and at sea, floods, droughts, hurricanes, typhoons and cyclones, tornados, cold and heat waves, etc. Forest fires.