Question

Earthquake are common in the belts of young fold mountains

Answer 1

Yes, because most of the young fold mountains like Himalayas, Rockies, Andes, etc. are favourable for Earthquakes.

Answer 2

The earthquakes are more common in the belt of the young fold mountain because they are composed of weak sedimentary rocks which are easy to fold due to their softness. So, the chances of techtonic movement becomes more prevalent and there are more chances of earthquakes in such regions - they are even more intense.