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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
Give a geographical reason.
Buildings collapsed at the foothills of the Himalayas because of an earthquake. Before collapsing, they were moving forward and backward.
Identify and name the internal movement.
Molten magma is thrown out of the earth’s mantle.
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:
Most earthquakes occur on account of the strain in the _________.
State two natural causes of an earthquake.
What are known as seismic focus and epicenter with respect to 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. |
How are earthquakes distributed over the globe?
How is the intensity of an earthquake measured?
What is an Earthquake?
Name the instrument used to record Earthquakes.
Name some Earthquakes which caused great damage.
What was the cause of the Koyna earthquake in India?
Give reasons for the following:
Folding and faulting frequently go together.
The earthquake is measured by the ______ scale.
The earthquake is a ______ activity.
An earthquake of magnitude ______ scale can cause damage from things falling.
What is the point of the earth’s surface directly above the focus called?
