Ways to design details of crack lines? ("earthquake")

[Alexx31]

Hello,

I have a special question:
Are there ways to design the lines of cracks?

1. to make them jaggy

2. to let broken parts crack more just from their edges? sometimes chunks break not sharp, they get more round edges because the edges were crushed.

I am trying if it's possible to reproduce an earthquake look, when looking close (not from far away)...
I have attached a rough test and 2 screenshots, in which direction I am looking.

Thanks for any tip!