Scientists Warn of San Andreas Earthquake 60 Times Stronger Than ’94 Northridge
Earthquake scientists are warning southern Californians to get prepared now- the San Andreas fault is long overdue for a major earthquake.
A new computer simulation unveiled last week at the National Earthquake Conference in Long Beach (and being covered by Forbes, the Smithsonian, the LA Times) demonstrates a release of pent up friction in southern California’s section of the San Andreas fault. Seismologists say the overdue quake could reach 8.0 and shake for up to two minutes.
They believe an earthquake of that magnitude in the LA area could kill 1,800 people, injure another 50,000, and cause damages upwards of $200 billion, and are encouraging people to have earthquake bags on hand and get prepared now.
“We think Southern California is locked and loaded, that the stresses have really built up, and when things start unleashing, they could unleash for years,” says U.S. Geological Survey seismologist Ned Field. “Everyone should live every day like it could be the day of the Big One, because any day, even today, could be that day.”
Thomas Jordan, director of the southern California Earthquake Center, agrees. The San Andreas is the backbone of the region’s fault lines, and is troublesome because it generates the most dangerous quakes for residents, Jordan notes.
Many Angelenos use the 1994 Northridge earthquake for context, as it was the most recent large quake to rock the L.A. Basin. Experts say the San Andreas fault release they warn of would be about 60 times stronger than ‘94 Northridge.
Why are scientists so worried now?
The San Andreas hasn’t created a big earthquake in this region since a 7.9 earthquake struck Fort Tejon in 1857, 159 years ago. To Palm Springs and south there hasn’t been a rupture in over 300 years. “Eventually the fault will have to break,” Jordan says.
It’s a matter of math and probability. On average, southern California sees a major earthquake every 110-140 years, so the region is overdue by 20-50 years. The San Andreas has moved an average of 2” per year over the last several million years, meaning average plate movement has pent up 26 feet of force since then. All that built up strain will eventually overpower friction with surrounding rock, and has enough ammo to unleash a violent earthquake- experts say a rupture up to 8.0 magnitude.
Southern California ‘Locked and Loaded’
What truly alarms scientists is that quakes rarely come one at a time in southern California. An incredible amount of stress has accumulated across both the San Andreas and the San Jacinto Faults. A single earthquake rarely removes all the stress in a fault line; it will most likely push it further down the fault line, so one quake sets off others. A rupture on one fault line likely triggers a release across the region’s splintered fault network.
A case in point, the 1857 Fort Tejon quake actually began 185 miles north in Monterey county before steaming south through L.A. county and points southeast. The quake was so powerful, even 185 miles from its epicenter, that the soil liquefied causing trees to sink and uproot.
But damage from a series of quakes is only the beginning.
“Imagine America without Los Angeles”
The report expects hundreds of fires to start from broken gas lines and damage in the aftermath of southern California’s next major earthquake. Lines bringing gas, electricity and water to Los Angeles cross the San Andreas, and gas-fueled fires can spread while broken water lines make firefighting nearly impossible in areas. Aftershocks will shake the region for days.
USGS seismologist Lucy Jones believes is could be worse yet. She says the reporting team was surprised by the extent of fire damage from quakes in the simulation, but damage could be exponentially worse if Santa Ana winds are blowing. Blowing dry, dusty inland air toward the coast, they can spread fires rapidly. Experts urge residents to have a survival bag on hand with essentials prepared to shelter-in-place or having grab and go.
The death, injury and damage estimates are scary, but “it’s not so much about dying in the earthquake. It’s about being miserable after the earthquake and people giving up on southern California,” says Jones. The city and region rely on water and the electric grid, along with communication and road networks. The damage from an event like this could leave the region’s infrastructure damaged for a year or more.
“Imagine America without Los Angeles,” Jones posits.
How Should L.A. Prepare?
Scientists can’t predict when the next major earthquake will strike, but they do know that L.A. is overdue for a large and devastating earthquake. Experts like Jones are urging the public to focus on earthquake preparedness now before it’s too late.
“However much water you already stored, get some more… we’re going to lose all the aqueducts into southern California and most of the pipes coming into people’s houses,” said Dr. Jones. At the very least, people should be prepared to be self-sufficient for days and maybe weeks after an earthquake disaster.
If you live in the region, then having a survival bag prepared for you and your family is a must. It should include water, food, a radio and flashlight (ideally hand-crank powered), tools, hygiene items and first aid. Survival bag options like the popular Earthquake Bag can make the difference between survival and crisis in the face of a disaster.
(Sources: Forbes, Smithsonian, LA Times, CBS Los Angeles)
- Zach Miller