Amit;

You need a better understanding of plate tectonics, that's all.

Quakes within a plate are caused by differential stresses within the plate resulting from (for example) rotational stresse4s at the different borders.

Clusters of quakes are not as unlikely as you think. Mag 6+ quakes happen nearly every day globally so the chances of 2 or more on the same day are quite good.

I'm away from home for another week or so but when I get back I'll put some numbers to the answer.

Roger