Local geologists are looking at when the next big earthquake could occur in California.
Dr. Pat Abbott, professor of geology emeritus at San Diego State University, told Fox 5 San Diego, the southern San Andreas fault is particularly concerning when looking at places that are overdue for an earthquake above a magnitude 7.5, impacting areas like San Bernardino, Palm Springs and Imperial County.
That portion of the 700 mile-long fault has not had an earthquake around that size in magnitude since about 1690, Abbott said.
A 2008 projection behind the Great California ShakeOut estimated that a potential 7.8 earthquake in the southern section of the fault could have a death toll as high as 1,800.
But scientists are also especially worried about a smaller fault that’s overdue for a major earthquake: the Hayward fault, which runs directly under cities in the Bay Area.
“Part of the worry there is not just the magnitude, but the whole East Bay area is full of old cities that have a lot of old buildings,” Abbott said. “You could have a horrendous loss of life from a magnitude 6.5 earthquake.”
With these two areas of concern for seismologists, there are a number of potential scenarios that could play out in the earth’s crust – some of which could look a lot like the catastrophic, magnitude 7.8 earthquake in Turkey and Syria due to similarities in the way those faults are set up compared to California.
“We are challenged by these earthquakes happening so rarely,” said Alice Gabriel, associate professor of seismology with the Scripps Institute of Geophysics and Planetary Physics. “It’s just a very long timescale. Now, we have the Turkey events, which were very devastating but also have important lessons for us.”
One such lesson is the potential for a “doublet” earthquake, or additional earthquakes triggered along nearby faults to one that has a “big one.”
“Something that we saw in Turkey that is really difficult to predict, is that there wasn’t only one earthquake,” Gabriel said. “A magnitude 7.8 (was) the first event, but it triggered nine hours and a few minutes later, a second event that was almost as large.”
The Hayward fault would be a candidate for a secondary earthquake that is dynamically set off if an earthquake, like a 7.4, were to hit in Southern California, she said, considering how much stress has already built up between the plates – mirroring what was seen in Turkey.