Magnitude of Earthquake


 
 
Concept Explanation
 

Magnitude of Earthquake

Magnitude of an Earthquake: The most common scale used to measure the magnitude of an earthquake is the Richter scale. An earthquake of magnitude 2.0-4.0 on the Richter scale is not too damaging. One of magnitude 4-8 is considered a moderate to severe earthquake. An earthquake of magnitude greater than 8-9 would be very severe.  On 26 January 2001, there was a major earthquake of magnitude 7.6-8.1 in Gujarat. Records of earthquakes

  • The very biggest earthquakes ever recorded have magnitudes in the range of 8.5-9.5. Earthquakes with magnitude greater than 7.5 are called "great", those in the range of 6.5-7.5 are"major", those between 5.5 and 6.5 are termed "large" and those of magnitudes 4.5-5.5 are"moderate". The rest are "small". Big earthquakes are less frequent than little ones. Each year more than a million earthquake happen. 
  • The earthquakes which was most destructive of human life was the Shansi Province, China, event of 1556 (magnitude unknown) which killed 830,000 people, although China came close to that again when 650,000 perished in the magnitude 7.6 Tangshan Province event of 1976. Out of the 9 earthquakes known to have killed more than 100,000 people, 6 occured in china, 2 in Japan and 1 in India.
  • MagnitudeEarthquake effect
    2.5 or lessUsually not felt, but can be recorded by seismograph.
    2.5 to 5.4Often felt, but only causes minor damage.
    5.5 to 6.0Slight damage to buildings and other structures.
    6.1 to 6.9May cause a lot of damage in very populated areas.
    7.0 to 7.9Major earthquake. Serious damage.
    8.0 or greaterGreat earthquake. Can totally destroy communities near the epicenter.
    Sample Questions
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    Question : 1

    Which of the following are correct :

    (a) When the magnitude of earthquake is 2.5 or less,it usually not felt, but can be recorded by seismograph.

    (b) When the magnitude of earthquake is 2.5 or less,it is great earthquake. Can totally destroy communities near the epicenter.

    (c) When the magnitude of earthquake is 8 or more,it is great earthquake. Can totally destroy communities near the epicenter.

    Right Option : C
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    Explanation
    Question : 2

    Earthquakes with magnitude greater than 7.5 are called ______________________.

    Right Option : A
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    Explanation
    Question : 3

    The instrumental scales used to describe the magnitiude of an ___________ began with the Richter magnitude scale in the 1930s.

    Right Option : A
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    Explanation
     
     


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