In this March 17, 2014, file photo, Egill Hauksson a Caltech Seismologist talks about an early morning earthquake during a news conference at Caltech in Pasadena, Calif. A new study says an earthquake fault running from San Diego to Los Angeles is capable of producing a magnitude-7.4 temblor that could affect some of the most densely populated areas in California. (AP Photo/Nick Ut, File/AP Photo/Rich Pedroncelli, File)
Whose fault? Blame the earthquake
March 14, 2017
An earthquake fault runs from San Diego Bay to Los Angeles. It is in Southern California. The fault is capable of producing a magnitude-7.4 earthquake. That could affect some of the region's most densely populated areas. This is according to a study released March 7.
The study looked at the Newport-Inglewood and Rose Canyon systems. These previously were thought to be separate. The researchers concluded the systems actually form a continuous fault. It is underwater. It runs from San Diego Bay to Seal Beach in Orange County. On land, it runs through the Los Angeles basin.
The fault poses a significant hazard. It could impact coastal Southern California and Tijuana, Mexico, according to the study.
It could produce up to a magnitude-7.3 quake if the offshore segments rupture. It could be a magnitude-7.4 quake if the onshore segment also ruptures. The study was conducted by Scripps Institution of Oceanography. It is at the University of California San Diego.
Even a moderate quake on the fault could have a major impact on the region. That is according to Valerie Sahakian. She is the study's lead author.
"This system is mostly offshore but never more than four miles from the San Diego, Orange County, and Los Angeles County coast," Sahakian was quoted in a press release from the American Geophysical Union.
The fault's most recent major rupture occurred in 1933 in Long Beach. It produced a magnitude-6.4 earthquake. It killed 115 people.
The study looked at data from previous and new seismic surveys. These included sonar studies of the offshore fault. Researchers looked at four segments of the fault that were offset. These are known as stepovers. The researchers found the disconnections weren't wide enough to prevent the entire offshore section of the fault from rupturing.
Researchers also looked at the onshore segment of the fault. They concluded that there have been three to five ruptures in the past 11,000 years along the northern section. One quake occurred about 400 years ago at the southern end.
Researchers at the Nevada Seismological Laboratory assisted with the study. It was funded by Southern California Edison. The study was accepted for publication in the American Geophysical Union's Journal of Geophysical Research.
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CRITICAL THINKING QUESTION
Why do so many people live in California, despite the earthquake risk?
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