Bad news for California.
The U.S. Geological Survey just released a new study, revealing that the Grapevine – which is just north of Los Angeles, running along Interstate 5 – could be due for a major earthquake.
On average, they found that the Grapevine has had an earthquake every 100 years and it’s been 160 years since the last quake rattled the area.
The USGS also found that each side of the San Andreas fault line (which runs through the Grapevine) has pushed against itself at an alarming rate – measuring about 1 inch a year since 1857.
“So you expect that amount of accumulation of energy will be released in the future in a large-magnitude rupture, somewhere along the San Andreas,” Kate Scharer, a research geologist for the USGS said, via L.A. Times.
If an earthquake, similar in size to the quake of 1857 occurred, channels that move water into southern California from the north, transmission lines and the I-5 freeway could each be affected.
On top of that, the USGS estimates that the shaking could be felt all the way in central L.A. for a “couple of minutes.” While that may not seem too long, the Northridge earthquake – which devastated areas all around the Southland — only shook for roughly 15 seconds.
“This would be more broadly felt across the basin,” Scharer explained. “It would impact our ability to be a world-class city.”
The news is rather disturbing, especially because the San Andreas fault line has generated more and more strain, without major release, since 1853.
The USGS also found that the average size of the 10 quakes examined over the past 1,200 years was a 7.5 in magnitude – meaning a disaster of this size would have the ability to rip through land all along the fault line and move it by an average of 9 feet!
While their findings are startling, there’s still no saying when the next “big one” will occur. The longest gap between quakes was about 200 years with the shortest occurring just 20 years after the last significant seismic activity in the area.
“Longer gaps have happened in the past, but we know they always do culminate in a large earthquake. There’s no getting out of this,” Scharer stressed.
In the case of a 7.8 earthquake or higher, the USGS found that five high-rise steel buildings and 50 concrete buildings in L.A. would be susceptible to collapse.
Luckily, areas like Los Angeles, Santa Monica and Santa Barbara have started to pass legislation requiring the retrofit of concrete and steel-frame buildings identified as “vulnerable” in the face of a major earthquake.
Julian De La Torre is an expert in Los Angeles foundation inspection, foundation contractors and foundation repair. Julian’s company, Julian Construction, has inspected over 15,000 structures, working with engineering firms and local departments of building & safety. The company has done more foundation repair in Los Angeles than any other company in the area over the last five years.