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.

Source: Ridgecrest earthquakes show how small faults can trigger big quakes – Los Angeles Times