East of the Sierra Nevada's is a group of active fault lines that have been involved in at least 17 major earthquakes in the past 1,400 years.
A study published this month in Tectonics posits that they're due for another moderate to major quake. Stress accumulation in the fault lines is most likely built up from previous earthquakes.
This type of stress accumulation, that results from stress moving along fault lines as a result of other quakes, is called Coulomb stress. The research team studied past earthquakes in the region to determine whether they were caused by Coulomb stress, or if they happened at random.
Though the study concluded that the group of faults is likely next in their region for a moderate to major quake event, it is not imminent, and it's not possible to know exactly when it will happen.
"The spatial distribution of earthquakes in this region is not a random process," lead author and geologist at the Ludwig Maximilian University of Munich Alessandro Verdecchia said in a release.
"If we model these stress changes, we can see if a fault may be prone, perhaps ready, to produce an earthquake."
Unlike the San Andreas fault, the boundaries of the tectonic plates involved in the study have less clear patterns. The faults are smaller, slower and affect a larger region.
Earthquakes in the studied region occur less often than ones along the San Andreas fault. 1,400 years of data was analyzed in search of a pattern.
The team built a model and used the data to understand how and why earthquakes happened in the region. They found that most of the quakes were linked to Coulomb stress.
Six of the studied faults have accumulated enough Coulomb stress to trigger an earthquake. These particular faults are due for one as they haven't produced a quake in more than 1,000 years.