In 1906, a powerful 7.9 magnitude earthquake caused the deaths of up to 3,000 people and destroyed more than 80 percent of the city of San Francisco.
Geologists have identified a new type of fault movement at San Andreas.
New evidence has found that the San Jacinto Fault zone, in California, is not as quiet as we thought and may be due for a big quake.
The finding helps us understand what triggers earthquakes—and when they are more likely to strike.
The fault continued to slip for 12 years after the 2004 Parkfield earthquake—a level of movement that has major implications for the Hayward Fault, which is set to rupture near San Francisco.