Concord fault line further west than once thought, scientists say

Researchers discovered a nearly 4-and-a-half mile stretch through the Ygnacio Valley area

Thursday, July 10, 2025

A fault line that could unleash a major earthquake is not where scientists thought it was.

CONCORD, Calif. (KGO) -- A fault line that could unleash a major earthquake is not where scientists thought it was.

New research found the Concord Fault is about a quarter mile west of where it was originally mapped.

It runs about 20 miles through Walnut Creek and Concord.

Researchers discovered a nearly 4-and-a-half mile stretch through the Ygnacio Valley area.

Neighbors tipped scientists off with reports of broken water lines and shifting sidewalk edges.

The research could affect construction standards and property values near the fault.

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