fault line

American  

noun

Geology.

1. the intersection of a fault with the surface of the earth or other plane of reference.

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fault line British  

noun

1. Also called: fault plane.  geology the surface of a fault fracture along which the rocks have been displaced

2. a potentially disruptive division or area of contention

   Europe remains the main fault line in the Tory Party

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Etymology

Origin of fault line

First recorded in 1865–70

Example Sentences

He astutely flags “medical gatekeeping” as an emerging fault line.

From The Wall Street Journal • Feb. 8, 2026

“The deeper fault line here is not trade flows. It is capital,” wrote Stephen Innes, managing partner at SPI Asset Management, in a Sunday note.

From MarketWatch • Jan. 19, 2026

The Hamaoka plant is located in Omaezaki, Shizuoka prefecture, near a seismic fault line where a massive Pacific earthquake is expected to occur in the coming years or decades.

From Barron's • Jan. 6, 2026

"This is significant because it means the ground shaking near the fault line might be more intense than our current hazard models predict for these types of faults."

From Science Daily • Dec. 16, 2025

The massacres had happened over two hundred years ago, but the wound they’d made in our cultural history was left raw and festering, like a fault line that may begin trembling again at any moment.

From "The City Beautiful" by Aden Polydoros

Related Words

• rift