Researchers have discovered a new fault line in Southern California that may impact the San Andreas Fault which runs through the state, according to a study published on Wednesday by the Scripps Institution of Oceanography from the University of California, San Diego.

UC San Diego partnered with the Nevada Seismological Laboratory at the University of Nevada in Reno for the study.

The San Andreas Fault is the longest in California, unleashing a magnitude-7 earthquake every 175 to 200 years, according to the study. But there have not been any major quakes in the last 300 years.

Last week, a cluster of small earthquakes near the southern end of the San Andreas Fault raised the probability of a magnitude-7 quake hitting Southern California in the near future.

Now, researchers have discovered the Salton Trough Fault, which runs parallel to the San Andreas Fault.

Neal Driscoll, a geologist at Scripps and the coauthor of the study says that the fault was not detected earlier because of two reasons—its location and lack of seismic activity in that area.

But the study states that further research is needed before the relationship between the two faults can be determined.

“Based on the deformation patterns, this new fault has accommodated some of the strain from the larger San Andreas system, so without having a record of past earthquakes from this new fault, it’s really difficult to determine whether this fault interacts with the southern San Andreas Fault at depth or in time,” said Nevada State Seismologist Graham Kent, a coauthor of the study and former Scripps researcher.