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प्रश्न
How an earthquake is caused?
उत्तर
Causes The chief known causes of earthquakes are believed to be as follows :
- When a dormant volcano erupts into activity or an active volcano discharges matter with greater violence the surrounding areas feel tremors or earthquakes.
- When the interior of the earth cools and contracts the outer crust in some places cracks and faults are caused. This movement causes an earthquake.
- Some time water percolates so deep down into the earth that it turns into steam on account of the internal heat. This steam expands and tries to force its way out. This pressure causes an earthquake.
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संबंधित प्रश्न
Give geographical reason.
Buildings collapsed at the foothills of the Himalayas because of an earthquake. Before collapsing they were moving forward and backward.
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.
Give reasons why an earthquake occurs.
Fill in the blank:
The giant sea waves caused by earthquakes in the oceans are called ___________.
Fill in the blank:
About 70 percent of the earthquakes occur in the _________________ Belt.
State two natural causes of an earthquake.
Name one man-made cause of an earthquake.
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. |
What is an Earthquake?
Describe the world’s distribution of earthquakes.
Name the instrument used to record Earthquakes.
Name some Earthquakes which caused great damage.
Why are earthquakes related to volcanoes?
Give reasons for the following:
The Belts of volcanic activity and earthquakes are roughly the same.
Define Earthquake.
On an outline map of the world, mark the Pacific Ring of Fire
The earthquake is measured by the ______ scale.
In India, the Himalayan region and the ______ valley are prone to earthquakes.
Name the point where the vibrations originate in an earthquake.
