Report Shows California Fault Could Generate Magnitude-7.4 quake

  • Report Shows California Fault Could Generate Magnitude-7.4 quake

Report Shows California Fault Could Generate Magnitude-7.4 quake

If the offshore segments erupt, researchers estimated a 7.3 magnitude quake; if the southern onshore segment also ruptures, researchers estimated a magnitude 7.4 quake.

Because the 1857 quake hit when the population was so small, only two people were killed. The Rose Canyon fault runs along a very populated area, which also makes it hard to study.

A fault system that runs from San Diego to Los Angeles is capable of producing up to magnitude 7.3 earthquakes if the offshore segments rupture and a 7.4 if the southern onshore segment also ruptures, according to an analysis led by Scripps Institution of Oceanography at the University of California San Diego.

They identified four segments of the strike-slip fault that are broken up by what geoscientists call stepovers, points where the fault is horizontally offset. However, along the Newport-Inglewood/Rose Canyon fault zone, none of the three stepovers exceed 2 km in width, leading the team to believe that an natural disaster could rupture the entire length of the fault zone in M=7.3+ events.

The study looked at data from previous and new seismic surveys that included sonar studies of the offshore fault.

The Fort Tejon 7.9-magnitude natural disaster in 1857 was the last major quake to occur along the San Andreas Fault, which killed two people.

The fault runs underwater from San Diego, through Orange County to the Los Angeles basin, researchers said.

Even a moderate quake on the fault could have a major impact on the region, according to Valerie Sahakian, the study's lead author. The disparate data have different resolution scales and depth of penetration providing a "nested survey" of the region.

The alarming study was detailed in the most recent edition of the American Geophysical Union's Journal of Geophysical Research.

After drawing up a map of what was underneath, researchers found proof of what they'd suspected for years; the gap between the two systems was only 1 1/4 miles apart from each other, not 3 miles, as reported in the past.

Scientists said that more work is needed to explore the risk that the quake system could pose to coastal cities such as Los Angeles and Tijuana.

Even though we witnessed the San Andreas fault trigger a devastating natural disaster in Los Angeles via Hollywood magic in 2015, the last major quake in that region actually occurred in 1857.

Friday, March 10 is the anniversary of Long Beach natural disaster in 1933, the deadliest California quake in 100 years. On the south end, which goes through San Diego, there is evidence a quake happened roughly 400 years ago, but there is little significant activity for the 5,000 years prior.