"Two fault lines previously thought to be separate systems are actually connected, say scientists. Together, they could bring intense shaking to some of Southern California's most populous areas."

"The Newport-Inglewood and Rose Canyon systems, which were previously thought to be separate, actually form a continuous fault line that could produce a major earthquake in the region, according to a study published Tuesday in the American Geophysical Union's Journal of Geophysical Research.

The single fault system, which runs underwater from San Diego Bay to Seal Beach in Orange County and on land through the Los Angeles basin, poses a significant threat to some of the most densely populated areas along coastal Southern California and Tijuanna, Mexico, wrote seismologists from the University of California, San Diego and the University of Nevada, Reno.

By looking through data from previous and new seismic surveys, including bathymetric data gathered offshore, the researchers estimated that the fault could cause up to a magnitude-7.3 quake if the offshore segments rupture and a magnitude-7.4 quake if that rift extends onshore."

Mengqi Sun reports for the Christian Science Monitor March 8, 2017. [2]