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प्रश्न
Give a geographical reason.
Buildings collapsed at the foothills of the Himalayas because of an earthquake. Before collapsing, they were moving forward and backward.
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उत्तर
- The seismic waves can be divided into primary, secondary, and surface waves.
- When energy is released from the Earth’s interior, the primary waves are the first to reach the surface.
- Subjected to a ‘P’ wave, particles in the rock move to and fro in the direction of the wave; therefore, these waves are also called forward-backwards waves.
- Thus, during an earthquake, the buildings at the foothills of the Himalayas moved forward and backwards as they were first subjected to “P” waves.
- These movements create tremendous tension in the earth’s crust, and when the tension goes beyond limits, the energy is released in the form of waves, which is the cause of the trembling of the earth’s surface.
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संबंधित प्रश्न
For the formation of a rift valley, which of the following processes should occur in the earth’s crust?
Arrange the following statements in chronological order in which an earthquake occurs.
- The earth’s surface vibrates.
- The plates suddenly move.
- Due to the movements in the mantle, compression goes on increasing.
- Along the weak points ( faultlines) rocks break apart.
- Stored energy is released in the form of seismic waves.
Fill in the blank:
The last of the earthquake waves to arrive on the surface of the earth are ___________ waves.
Fill in the blank:
The giant sea waves caused by earthquakes in the oceans are called ___________.
Match the Columns.
| Column A | Column B |
| 1. Tsunami | (a) The waves that make the inhabitants feel the ground motion. |
| 2. Seismograph | (b) The instrument for measuring the intensity of earthquakes. |
| 3. S-waves | (c) Harbour waves generated by oceanic earthquakes. |
| 4. Richter scale | (d) The point on the earth surface directly above the seismic focus. |
| 5. Epicentre | (e) An instrument for recording the movement of earthquake waves. |
Name the instrument used to record Earthquakes.
What was the cause of the Koyna earthquake in India?
Give one word for the following :
An instrument used for recording all the earth tremors and earthquakes.
The earthquake waves are recorded by an instrument known as ______.
What is the point of the earth’s surface directly above the focus called?
