The crack is actually a result of the DIE that struck this particular silver strike being cracked ... not the strike itself.

Keep in mind, what one sees raised on the surface of a coin/strike is actually recessed on the die. So in this case, with the die being cracked due to excess pressure during the striking process ... all coins struck after the die has cracked will show this raised line on the coin where the metal flowed into the recess of the crack.