Fresh after a swarm of almost 200 earthquakes hit Southern California earlier in the week, researchers from the University of California San Diego's Scripps Institution of Oceanography and the University of Nevada's Nevada Seismological Laboratory released a study detailing their discovery of a new fault along the Salton Sea's eastern edge.
The Salton Trough Fault is situated parallel to the San Andreas Fault and could be potentially significant given its possible impact on seismic hazard models currently in place in the earthquake-prone region.
Publishing their findings in the Bulletin of the Seismological Society of America, the researchers said identifying and locating faults correctly before earthquakes hit is important as this can aid in assessing seismic hazards more accurately, which can then help in reducing risk.
"The location of the fault in the eastern Salton Sea has made imaging it difficult and there is no associated small seismic events, which is why the fault was not detected earlier," said Neal Driscoll, Scripps geologist and co-author of the study.
In identifying the new fault, the researchers turned to seismic equipment for marine use in getting a better look at deformation patterns under the sea that blocked the fault's location. With ocean-bottom seismometers, light detection and ranging and multi-channel seismic data, they were able to accurately map the deformation patterns present within layers of sediment in and around the bottom of the sea.
According to recent studies, the area has been experiencing magnitude-7 level earthquakes every 175 to 200 years over the course of the last 1,000 years. However, in the past 300 years, a significant rupture in the San Andreas Fault's southern section has not happened.
Graham Kent, also a co-author of the study, said this is puzzling. Going by the deformation patterns they were able to capture, Kent and colleagues are saying that the new fault absorbed some of the pressure from the bigger San Andreas system. However, because no earthquakes in the past have been attributed to the Salton Trough Fault, they are not able to tell if the new fault will interact in time with the San Andreas Fault's southern section or if an interaction is already happening at depth.
Since the swarm of smaller earthquakes increased the likelihood of a major one hitting Southern California, the California Office of Emergency Services issued a warning for residents of San Diego, Los Angeles, Orange, Ventura, Riverside, San Bernardino, Imperial and Kern counties of the possibility that a major earthquake could hit the area in the coming week.
According to the U.S. Geological Survey, the seismic events recorded since the morning of Oct. 3 ranged in magnitude between 1.4 and 4.3.