Scientists thought before that the fault lines in San Diego, Los Angeles and Orange in California are all separate. However, after some research, they found out that they were all connected and can produce a gigantic earthquake with 7.3 magnitudes.

The Newport-Inglewood and Rose Canyon faults were once thought separate but are actually one continuous fault system. It runs from San Diego Bay to Seal Beach in Orange County, and then on land through the Los Angeles basin, Scripps Institute of Oceanography reported. The research was from "Seismic constraints on the architecture of the Newport-Inglewood/Rose Canyon fault: Implications for the length and magnitude of future earthquake ruptures," which appeared in the American Geophysical Union's Journal of Geophysical Research.

The fault line system is mostly offshore but they are very near, just four miles, to San Diego, Orange County, and Los Angeles County coast. "Even if you have a high 5- or low 6-magnitude earthquake, it can still have a major impact on those regions which are some of the most densely populated in California," said study lead author Valerie Sahakian, who performed the work during her doctorate at Scripps and is now a postdoctoral fellow with the U.S. Geological Survey.

Data from old seismic surveys were studied, the researchers said. With those Scripps researchers combined it with high-resolution underwater topography data gathered offshore between 2006 and 2009, KPBS stated. Information about the seismic surveys conducted in Scripps research vessels in 2013 was also gathered. The dissimilar data have diverse resolution scales and depth of infiltration. It led the scientists to identify the fault architecture at an unparalleled scale and make magnitude estimates with more assurance.

After using the two different methods to find what will be the estimated magnitude of the earthquake, if there will be any, it was between magnitude 6.7 and magnitude 7.3 to 7.4. The said fault system in California produced the infamous 6.4-magnitude quake in Long Beach that killed 115 people in 1933. More other evidence of earthquakes was found in the onshore parts of the fault line. In the last 11,000 years, more than three to five ruptures happened.