Consider the following statements about earthquakes and identify the correct one s 1 ...........

Geography Earth Geology

Consider the following statements about earthquakes and identify the correct one/s.

1. The foci of the earthquakes in the areas of mid-oceanic ridges are at shallow depths whereas the earthquakes along the Alpine-Himalayan belt and the Pacific coast are deep seated ones.

2. The shallow focus earthquakes are more common than the deep seated ones.

3. The shallow focus earthquakes are more destructive than the deep seated earthquakes.

Select the correct answer using the codes given below

1 and 2 only

2 and 3 only

3 only

All of the above

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Explanation:

SHALLOW FOCUS earthquakes are commonly occurring crustal earthquakes. These are earthquakes with their focus nearer the surface of the earth. These occur quite frequently and at random. However, being of smaller magnitudes and at lesser depths, very often they are not even felt. Nevertheless, about 75 % of the world’s energy released from earthquakes is from shallow-focus ones.
Deep focus earthquakes are known as intra plate earthquakes, as they are triggered off by collision between plates. They happen as huge quakes with larger magnitudes, as a great deal of energy is released with the forceful collision of the plates.
Shallow focus earthquakes are of smaller magnitudes, of a range 1 to 5, while deep focus earthquakes are of higher magnitudes, 6 to 8 or more.
Shallow-focus earthquakes occur at depths less than 70 km, while deep-focus earthquakes occur at greater focal depths of 300 – 700 km.
The Alpine-Himalayan belt and the Pacific coast are zones of subduction where plates are getting consumed. As such the seismic forces generated here are deep-seated ones as subducting plate margins are deep seated.