fault line

• faultline, fault-line

fault line (plural fault lines)

1. (geology) The line formed by the intersection of the plane of a fault with the surface of the Earth
2. (by extension) A minor split (in public opinion etc.) that may develop into something larger.
   • 2016 October 22, Rami G Khouri, “Lebanese oligarchy preserves its interests once again”, in Aljazeera‎^[1]:

     Yet the process may lead to new fault lines and resentments across the notoriously unstable Lebanese political system whose 18 different confessional groups share all levels of power.

• Feuillant