Simply, it's when the surface of the Earth shakes.
All the time. Mostly you don't feel them.
Pressure builds up along fault lines. Sometimes that pressure gets released. When it does, the energy flows through the planet and shaking happens.
Basically a crack in the earth. There are a few different kinds.
Normal faults crack where one mass of rock slides downward and pulls away from another mass of rock.
A strike slip fault occurs in an area where two tectonic plates are sliding past each other. The San Andreas fault, which extends about 750 miles through California, is probably the most well-known slip-stike fault.
A thrust, or reverse, fault results when two tectonic plates are pushed together and buckle upward as the plates collide.
There are more than 500 known, active faults in our great state of California. But scientists are still discovering ones they didn't know existed. To visualize exactly how many faults lie beneath your feet, think about a bowl of spaghetti. Now take a handful of noodles and throw them on a map. That's about what we’re dealing with here. For a more precise visual, type your address into the map below and see if you're standing above a known fault.
These mean different things when talking about the severity of an earthquake. Magnitude is a quake's quantitative size. It's measured by how much seismic energy is released at the underground source of the quake. Intensity is the observed effects.
The U.S. Geological Survey groups quakes on a magnitude scale from "Minor" to "Great."
|Great||8 or more|
|Major||7 - 7.9|
|Strong||6 - 6.9|
|Moderate||5 - 5.9|
|Light||4 - 4.9|
|Minor||3 - 3.9|
Most of the earthquakes on record do not meet the USGS classification of “Strong.”
The magnitude of the quake, how deep or shallow it hits, the size of the fault, the speed of the tectonic plates and a bunch of other factors. But for you, the biggest factor will be how close you are to the epicenter of the quake. So...you might want to look at that map above.
July 2019. The Ridgecrest earthquakes that hit on July 4 and July 5 with a magnitude 6.4 and 7.1, respectively, were the most recent major earthquake in Southern California. The 7.1 lasted 12 seconds and was felt by about 30 million people. More than 6,000 lost power. These earthquakes followed a 25 year "quiet period" after Northridge, which was a 6.7 magnitude earthquake that killed 58, injured more than 9,000 and caused more than $49 billion in economic loss. That quake lasted less than 20 seconds. In 2010, a 7.2 quake hit in Baja, and it was felt in parts of SoCal. That Easter Sunday quake and the Ridgecrest quakes had a higher magnitude than the 1994 Northridge quake, but were less damaging.
Aykui Alaverdyan walks over rubble after taking some of her belongings from her Hollywood Boulevard apartment building on January 20, 1994 that was destroyed in the Northridge earthquake. Thousands of Angelenos were driven from their home following the 6.7 magnitude quake. (Tim Clary/AFP/Getty Images)
The Big One will be at least 11 times stronger than the Ridgecrest earthquake and 44 times stronger than Northridge.
Yes. When we refer to "The Big One" we mean a 7.8 magnitude (or higher) quake striking along the southern San Andreas fault. The higher magnitude means it will also last longer than Northridge, but where you are is going to play the largest factor in how this quake feels to you.
No. And the Westside is not going to fall into the ocean either. Tsunamis are much more likely in subduction zones and the San Andreas fault is not a subduction zone. So at least we have that. But if a major quake was to hit on a different fault...well.
According to the inventor of the entire field of paleoseismology, Kerry Sieh, big quakes like this occur on the southern San Andreas every 45-230 years and we haven’t had one in 161 years.
“We are certainly within the window of when that earthquake is going to happen. I'd be very surprised it didn't happen within the lifetime of children in primary school today,” Sieh told us.
OK. Here are some examples of what it might look like in different parts of the region.
Agreed. And it's just the beginning. According to The ShakeOut Scenario, a 7.8 earthquake hitting along the southern San Andreas fault on a non-windy day at about 9:00 a.m. will unfold, approximately, like this:
- 1,800 people will die
- 1,600 fires will ignite and most of those will be large fires
- 750 people will be trapped inside buildings with complete collapse
- 270,000 people will be immediately displaced from their homes
- 50,000 people will need ER care
- 11 days out, people will start to drink more
- Search and rescue efforts will last for 19 days
Seismologist Lucy Jones is pretty clear: “This will happen. We are not stopping plate tectonics.”
She and other scientists are sure that a big one is coming, even if we don’t know exactly where or when. “Just give it enough time,” she says.
The USGS has some tangible estimates on a "Strong" or "Major" event in Los Angeles in the next 30 years:
There's a 60 percent chance that it'll be an earthquake measuring magnitude 6.7m.
There's a 46 percent chance that it'll be an earthquake measuring magnitude 7m.
There's a 31 percent chance that it'll be an earthquake measuring magnitude 7.5m.
That last part is really important and too many people got bad information from the “Earthquake” episode of “Saved By The Bell” so please stay with us here. We're going over each action.
Do not run.
Do not run.
Do not run.
Once more for the folks in the back: Do not run.
If you run while the earth is shaking you are likely to sprain an ankle, break a leg or a myriad other injuries because the ground, again, is moving. Think about what might happen if you’re on a treadmill that unexpectedly starts moving.
This also applies if you're inside. Fight the urge to flee the building even if you are worried about becoming trapped in rubble. Outside is not safe. That’s because glass will be shattering out of windows and raining down onto you. What if there's a clearing outside, you say? Oh, what part of L.A. do you live in?
Get down on the ground before the earthquake throws you down onto the ground. For those of you who enjoy yoga, think of this as the Mother Earth submission pose.
Get under something to protect your neck and head.
Things are actually going to be flying through the air when this thing hits so unless you want to get a concussion from that copy of “Gravity’s Rainbow” you still haven’t finished, get under a table or desk.
Even the spindliest of desks can protect you.
Now that you are under something, you will want to stay there. So hold onto the leg of that table or desk lest you get tossed out by the literally moving ground (see above).
If you're not near a table or desk the next safest place is an interior wall away from windows. Do not get in a doorway. There is no science to back up getting in a doorway, and you know what else is usually in doorways? Doors. Don’t be the person who gets a black eye from a door when an earthquake hits.
Even if the Big One hits, the likelihood that you'll be in a building that completely collapses is pretty low. But it is a possibility. Some types of structures are stronger than others, with the performance dependent on a number of factors including: when the building was constructed, what it was constructed out of and the intensity of the ground shaking. Here are some common types of building damage to look out for in an earthquake.
Cracks: Visible cracks, especially "X" shaped, can indicate the building may be unsafe or structurally unsound.
Wall separation: Besides the obvious structural concerns, and the increased possibility of collapse, materials falling from the sides of buildings can be deadly. That's why running outside during the shaking is so perilous.
Multiple fractures: If cracks are numerous and severe, and there are obvious signs of structural deficiencies, like a lean in the building, evacuate immediately.
Illustrations by Dan Carino for KPCC
Most people in collapsed buildings can’t dig themselves out. They have to wait to be rescued. So if you're under a desk or table it'll help provide some air space to keep breathing. Please keep breathing.
Then quickly text as many people as you can with your location and medical status. After an earthquake, the "electricity is gone. And cell towers in general have four hours of backup power," says Jones. "If you're in [a collapsed building], send a text to people really quickly saying I'm trapped in this building.”
Don’t waste time calling 911. They will be inundated and most phone calls won’t be going through. Text is more reliable.
Make noise so people can find you. That said: “You don't want to scream," Jones says. "Screaming will dry yourself out and lose your voice before they get to you.” It also wastes oxygen.
Instead, try banging on something.
Keeping a couple bottles of water under your desk at work or in your home could be life saving. People trapped in collapsed buildings sometimes die of dehydration, not injuries.
You are more likely to get useful information from local media rather than national media after a major disaster. It is helpful to invest about $20 in a battery-powered radio (some of which are actually kind of cute!) so that you can keep up in the immediate aftermath.
It could be days before power is restored. Once it is and you are back online you can follow us of course — we will do everything we can to be up and running and to keep you informed. And these people too:
- L.A. City Emergency Alerts
- L.A. City Emergency Management Department
- L.A. County Office of Emergency Management
- L.A. Police Department
- LAPD Chief Michel Moore
- L.A. Sheriff's Department
- L.A. County Sheriff Alex Villanueva
- L.A. Fire Department
- LAFD Air Ops
- LAFD Chief Terrazas
- L.A. Mayor
- Cal OES
- The Governor
- L.A. Unified School District
- LAUSD Superintendent Austin Beutner
If you have a cell phone in California you will receive Wireless Emergency Alerts from Cal OES on your phone. These alerts look like text messages but are accompanied by a loud, unique sound (i.e. those Amber Alert messages you get every so often) in order to get your attention.
The governor of California will first declare a state of emergency. Then the President will then confirm or deny the disaster declaration. Once confirmed, you will then hear proclamations pretty much everywhere there is power through Cal OES’s Emergency Alert System. This system “requires broadcasters, cable television systems, wireless cable systems, satellite digital audio radio service (SDARS) providers, and direct broadcast satellite (DBS) providers to provide the communications capability to the President to address the American public during a national emergency.”
Initially, the most reliable way to reach out to people for help or a check-in will be by text.
If you have wireless capabilities, you can notify others that you are safe through Facebook’s Crisis Response feature, which includes a “Safety Check” so that you can mark your status during a disaster. Apple also has a “Find My Friends” app that gives you access to your friends’ and family members’ locations and vice-versa. The Red Cross has a Safe and Well registry where you can list yourself and leave messages for your loved ones.
If wireless networks aren’t working and the power is out, you might have to rely on word of mouth. Check in with your neighbors. Or, once shelters are up and running, you can register yourself there.
That depends on a multitude of factors: if you have gas, if you have money, if your home or apartment is damaged, if you’ve accounted for your family, and, in the immediate aftermath, if the roads you would take to get out are safe to use.
In some cases Angelenos may be asked to remain off the roads in order to clear the way for emergency vehicles. Then again, you could be ordered to evacuate because of aftershocks, ruptured dams, fires or other fallout.
According to the report, 1,600 fires could ignite after the quake with 1,200 of them being big fires. Many of those fires will grow and move and converge to make even bigger fires. There’s a good reason San Francisco’s 1906 earthquake is often referred to as the San Francisco Fire.
A gas main on fire throws flames into the air after it broke and exploded, destroying nearby homes following the Northridge earthquake. A total of 466 fires were reported on Jan. 17, 1994, three of which simultaneously broke out immediately following the earthquake and were due of the rupture of natural gas valve/mains. (Hal Garb/AFP/Getty Images)
If you're lucky enough to still have water coming into your house, that's great. But it's likely that somewhere along the delivery system a sewer pipe has cracked and leaked into the water supply. That is why you boil it. It's possible that L.A. could be on a boil water warning for 18 months after such an earthquake.
Reports of looting, violent crime and scams are often over-reported after a major natural disaster (making disaster zones feel like something out of “The Walking Dead”). In reality, the only crime that certainly goes up (understanding that crime is hard to track during disasters) is domestic violence.
Strangers. According to disaster research expert Joseph Trainor, you are much more likely to be helped by someone you don’t know than hurt by someone you don’t know when this earthquake hits. Trainor says that in disasters, 95 percent of people saved from danger are helped by other civilians who are perfect strangers.
There's also FEMA.
It is not FEMA’s job to make you financially whole again after an earthquake but you can get housing vouchers, emergency money and more. Download the FEMA app now and familiarize yourself, or call 800-621-3362.
These are the things you should have on hand when you register with FEMA:
- Social security number
- Address/location of where the damage happened
- Current mailing address
- Current phone number
- Insurance information
- Household income
- Routing & account numbers for your checking and/or savings account for direct deposit from FEMA
- Photos and description of your disaster-caused damage and losses
You’ll receive a 9-digit number from FEMA that you’ll want to keep on you at all times. If you’re a small business owner, you will want to call 800-659-2955 or go to SBA.gov/disaster for assistance or for an economic injury disaster loan.
If your house or apartment burns down, you do not need to pay rent.
"One of the basic tenets of being a landlord is that your unit has to be habitable,” says Yasmin Guzman, director of media outreach and education at the Housing Rights Center.
That means you need to have things like functioning heat, effective protection from the elements and working electricity. A full list of requirements can be found on page 38 of the California Tenants Rights Handbook.
Your mortgage, however, will still be due. Car payments will still be due. If your utilities are in working order, those bills are also due. Even if utilities aren’t working, it might be safer to pay and get reimbursed later in order to avoid future conflict.
If you use automatic payments, it will be important to contact your bank and lenders as soon as possible after a natural disaster to prevent overdrafting your account.
This is a good resource for understanding financial obligations and options after a major disaster.
This is a disaster-related question we have been asked many times over. And I don’t feel like you are hearing us.
“Most of the time under most circumstances, you're going to see people become the best version, the most altruistic version of themselves, especially in those first couple of minutes, and moments after the event,” said Joseph Trainor with the Disaster Research Center.
So, you can make up your own mind about guns, but we can tell you this: If you own a gun, you are more likely to be shot.
When we asked earthquake expert Lucy Jones what was in her earthquake bag she said, “Ha ha ha ha ha ha ha.”
Not because being prepared is funny but because the idea that everything you need will fit in one bag is ridiculous.
That said, here is an article laying out what you might need.
No. There is so much more. But if we had to pick one more thing to emphasize (other than water — buy water, my dudes), it would be to have your documents in order. Disasters of this magnitude are devastating and trust me when I say that the last thing you are going to want to have to deal with is paperwork. Keep deeds, titles, insurance, and all other important type papers backed up on the cloud and keep copies at home in fire safe boxes.
U.S. Seismic Hazard Map, 2014 (FEMA)
News flash, you still might have to worry about earthquakes. Here are some more hazard maps.
Contributions and additional reporting by Jacob Margolis and Dana Amihere
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