Advertisements
Advertisements
Question
How an earthquake is caused?
Advertisements
Solution
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.
RELATED QUESTIONS
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:
Most earthquakes occur on account of the strain in the _________.
Fill in the blank:
___________ are the first earthquake waves to be recorded on a seismograph of an earthquake.
Fill in the blank:
The giant sea waves caused by earthquakes in the oceans are called ___________.
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. |
What is the difference between seismic focus and epicenter?
How is the intensity of an earthquake measured?
Name the instrument used to record Earthquakes.
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 ______.
Seismology is the study of ______.
Choose the odd one
On an outline map of the world, mark the Pacific Ring of Fire
An earthquake of magnitude ______ scale can cause damage from things falling.
In India, the Himalayan region and the ______ valley are prone to earthquakes.
Name the point where the vibrations originate in an earthquake.
