The San Andreas Fault May Be Slipping Faster — Here's What to Know About It

The San Andreas Fault, a 800-mile-long strike-slip fault that runs through California, has been found by researchers at San Jose State University to be slipping faster than previously thought. This discovery, led by Kim Blisniuk, an Associate Professor of Geology at the university, is still under peer review and has not been published yet.

Blisniuk and her team examined a section of the fault in Sanborn County Park, Santa Clara County, California. They observed that the slip rate in this area remained consistent, unlike the prediction that it would slow down over time. The U.S. Geological Survey (USGS) defines slip rates as the speed at which the two sides of a fault move past each other annually. Typically, the Earth's crust shifts only a few millimeters to centimeters per year, leading to pressure buildup and earthquakes.

The findings could impact how scientists estimate long-term earthquake hazards in the region. Blisniuk noted that the consistent slip rate contradicts what was initially predicted, making it less surprising now that the data is available. She explained that the cities and infrastructure built on the fault line and the occurrence of earthquakes are already well-known.

Historically, the San Andreas Fault has been the site of several major earthquakes. The most significant of these was the Great 1906 San Francisco earthquake, measuring magnitude 7.9 and rupturing approximately 270 miles of the fault. This earthquake occurred on April 18, 1906, with a foreshock followed by a devastating 5.12 magnitude quake. The event left around 700 deaths, though the actual number may have been higher due to fire.

Another notable earthquake was the 1989 Loma Prieta earthquake, which struck on October 17, 1989, at 5:04 p.m. with a magnitude of 6.9. The quake produced thousands of aftershocks, with one measuring magnitude 5.2 and over 300 others of magnitude 2.5 or greater. The death toll reached 63, though thousands were injured and many more displaced.

Experts recommend being prepared for future earthquakes by assembling an earthquake kit with essential supplies and staying informed about earthquake safety.