Scientists say they've discovered a new fault line running along the eastern edge of the Salton Sea parallel to the San Andreas Fault.
The announcement, published this week in the Bulletin of the Seismological Society of America, follows a recent rash of almost 200 small earthquakes at the Southern California inland sea and heightened concerns about the "Big One."
Valerie Sahakian, a researcher with the U.S. Geological Survey and lead author of the study, said the newly named Salton Trough Fault has no connection to the recent quake swarm and the timing of the announcement is coincidental.
The U.S. Geological Survey said the swarm temporarily increased the risk of a bigger earthquake. Officials said that risk fell back to normal on Tuesday.
The largest quake in the swarm was a magnitude 4.3.
Early Wednesday, two smaller earthquakes shook land south of where the swarm was located. Sahakian said she hadn't studied those quakes and couldn't say if they were linked to the swarm or the Salton Trough Fault.
Sahakian said the discovery of new faults is becoming less common, particularity in well-surveyed Southern California. But this one was difficult to find because it appears to be under the water.
The research was a joint effort by seismologists from University of California, San Diego's Scripps Institution of Oceanography, where Sahakian studied, and the University of Nevada, Reno.
More research is needed to determine the fault's full length and location. That information can then be used to better gauge earthquake danger.
"Things like locations of the fault and expected magnitude at the fault are what's used to predict the maximum groundshaking a region can expect," Sahakian said.
Research suggests that over the past thousand years, the southern end of the San Andreas Fault has seen magnitude 7 earthquakes roughly every 175 to 200 years, although a major event hasn't occurred in more than 300 years.