July’s Ridgecrest Earthquakes Ruptured on at Least 24 Faults, New Research Shows

A USGS Earthquake Science Center Mobile Laser Scanning truck scans the surface rupture near the zone of maximum surface displacement of the magnitude 7.1 earthquake that struck the Ridgecrest area. (Credit: Ben Brooks / U.S. Geological Survey)

A USGS Earthquake Science Center Mobile Laser Scanning truck scans the surface rupture near the zone of maximum surface displacement of the magnitude 7.1 earthquake that struck the Ridgecrest area. (Credit: Ben Brooks / U.S. Geological Survey)

When an earthquake strikes, the instinct of many Californians is to ask: Which fault ruptured — the Newport-Inglewood, the Hayward, the mighty San Andreas?

But scientists are increasingly saying it’s not that simple.

New research shows that the Ridgecrest earthquakes that began in July ruptured at least two dozen faults. It’s the latest evidence of how small faults can join together to produce a large earthquake, and how those quakes can cover a wider area than expected.

The findings are important in helping understand how earthquakes can grow in the seconds after a fault ruptures, when two blocks of earth move away from each other. In areas blanketed by a crisscross pattern of faults, an earthquake on a smaller fault can destabilize bigger ones, beginning a process that leads to a much stronger earthquake.

Read the full story on LATimes.com.

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