The San Andreas faultline gets most of the attention, but a recent study showed coastal California may be in danger from a system of faults that scientists have thought until now were disparate faults.

The American Geophysical Union published a study Tuesday that showed the Newport-Inglewood and Rose Canyon fault systems, which geologists previously considered separate fault systems, are actually a single system that runs from San Diego to Los Angeles, increasing the likelihood of larger earthquakes than previously anticipated. Estimates ranged from magnitude 6.7 to magnitude 7.4. By contrast, the earthquake that hit central Italy in August, killing hundreds of people, was magnitude 6.2, and the earthquake that hit San Francisco in 1989, killing 69 people and causing billions of dollars in damage, was magnitude 6.9.

Ryan Porter, an assistant professor of geology at Northern Arizona University is available to discuss these findings and what this discovery could mean for earthquake activity in southern California. His research looks at using earthquake seismology, specifically in using earthquake seismic waves to study the subsurface and better understand plate tectonics. His specialty area is the North and South American Cordillera, which includes mountain ranges along the Pacific Coast.

CONTACT: Ryan Porter, assistant professor of geology, Northern Arizona University, (928) 523-2429 or [email protected]

Talking points• The findings of this study provide an important constraint on the geometry and potential behavior of the Newport-Inglewood/Rose Canyon fault zone. Previously, the zone was not well characterized because much of it was underwater.• Using shipborne seismic transmitters and receivers, researchers could map the extent of the fault zone, which provides information about the seismic hazard for southern California.• “This fault, like the San Andreas, helps accommodate the motion between the Pacific and North American plates, and a magnitude 7.4 earthquake on it would cause significant damage across the region.”