fault line

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun geology The line formed by the intersection of the plane of a fault with the surface of the Earth
• noun by extension A minor split (in public opinion etc) that may develop into something larger

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (geology) line determined by the intersection of a geological fault and the earth's surface