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प्रश्न
How an earthquake is caused?
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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.
संबंधित प्रश्न
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:
___________ are the first earthquake waves to be recorded on a seismograph of an earthquake.
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 ___________.
What are known as seismic focus and epicenter with respect to an earthquake?
What is known as the Richter scale?
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. |
How are earthquakes distributed over the globe?
Describe the world’s distribution of earthquakes.
Why are earthquakes related to volcanoes?
Give two major causes of earthquakes.
Give one word for the following :
An instrument used for recording all the earth tremors and earthquakes.
Give reasons for the following:
Folding and faulting frequently go together.
Define Earthquake.
What is Seismograph?
On an outline map of the world, mark the Pacific Ring of Fire
The earthquake is measured by the ______ scale.
How the earthquake can be recorded?
What is the point of the earth’s surface directly above the focus called?
