Catastrophic earthquake scenarios
have played out on the silver screen for decades,
terrifying viewers with quakes that can collapse skyscrapers
or topple entire cities.
Here's what will happen if the big one hits the West Coast.
On July 4, 2019, Ridgecrest, California,
was hit with a 6.4 magnitude earthquake
and then a 7.1 just one day later.
But neither of these compare to the long-awaited big one,
which scientists predict will eventually
rattle the golden coast.
But when it hits, what will that actually look like?
Here's what experts say could happen
in the seconds, hours, and days after the big one.
While experts can't know exactly when a quake will occur,
they have a pretty good idea of where.
California is located in a hot zone of fault lines,
the most notorious of them the San Andreas Fault.
John Vidale: You know, here in California you have dangers
from a number of different kinds of earthquakes.
The major danger is from the earthquakes
on the San Andreas Fault system.
Narrator: On average, the San Andreas Fault
ruptures every 150 years.
The southern parts of the fault have remained inactive
for over 200 years.
Vidale: We haven't had a big earthquake in
Southern California really since 1857.
Narrator: In other words, we're overdue for a major shake.
According to a 2008 federal report,
the most likely scenario is a 7.8 magnitude quake
that would rupture a 200-mile stretch
along the southernmost part of the fault.
Vidale: It's basically moving the ground several yards
over an area of 50 square miles.
So the power of a magnitude 7.8 earthquake
is probably close to the power
used in the whole state for a year.
Basically something that we as a civilization
have trouble creating, short of, like, a nuclear explosion.
Narrator: If you are near the epicenter of the earthquake,
it will be nearly impossible to stand.
Vidale: People have this idea of running out of bed,
out of their buildings, and that's a terrible idea,
because a lot of what we see in earthquakes is people
with broken legs and people who've run through glass.
The best thing to do, like we always say,
is duck, cover, and hold.
Get under some piece of furniture.
The main point is to protect your head and chest.
Narrator: During and immediately following the shaking,
buildings could collapse.
John Wallace: The number of buildings that were constructed
before about 1980 is really significant,
and most of these buildings
are very vulnerable to damage and collapse.
Narrator: In this time-lapse video,
you can see how building components would hold up
in a high-magnitude earthquake.
Wallace: 'Cause the San Andreas will produce
the kind of long-period shaking
which would be very damaging to very tall buildings,
say, in downtown LA, and Century City,
and Long Beach, and so forth.
Older steel buildings, the connections in them
have not necessarily been designed
to withstand the maximum forces
that actually can be generated.
Narrator: Unreinforced structures are the least stable,
but even buildings up to code could crumble.
John Stewart: The building code, with its
minimum requirements, does not ensure that the building
will be serviceable after an earthquake.
It's intended to not kill anybody.
There's a sense that if it's modern, code-designed,
it's earthquake-proof and everything should be great,
but that's not the reality.
Narrator: Five steel high-rises
could collapse completely, while 10 others
will be red-tagged, or unsafe to enter.
And, no, the quake would not cause a tsunami,
despite what movies would have you believe.
Vidale: To trigger a tsunami, it takes an earthquake
that moves the ocean floor,
and most of the San Andreas is on land,
so there would be a little bit of waves generated
from a San Andreas earthquake,
but nothing that would be dangerous.
Narrator: The quake could kill about 1,800 people
and leave 50,000 or more with injuries.
While people could die from falling debris
and collapsed structures,
the highest death toll would be from fires.
Vidale: Historically, they biggest hazard
from earthquakes has been fire.
In the 1906 earthquake there were 3,000 or 4,000 people
who were just caught in that wave of fire
that swept through the city.
Narrator: The aftermath of the big one
will wreak havoc on infrastructure and the economy.
Scott Brandenberg: Below our streets and our buildings
is this really complicated network of infrastructure
that could be damaged, and a lot of the things
we take for granted every day
won't be available anymore, right?
Like water, electricity,
being able to drive where you need to drive.
Narrator: Parts of the San Andreas Fault
intersect with 39 gas and oil pipelines.
This could rupture high-pressure gas lines,
releasing gas into the air
and igniting potentially deadly explosions.
Stewart: So, if you have natural-gas lines that rupture,
that's how you can get fire and explosions.
Narrator: And after the fires burn out,
one of the biggest concerns in a major earthquake
is access to fresh water.
The major aqueduct networks
that pump water into Southern California
all cross the San Andreas Fault
and could be seriously damaged.
Stewart: So we would be without the lifelines
that bring in imported water to the region.
They cross through tunnels,
cross through aqueducts near the surface.
All of these would be ruptured,
and so we would be losing 60% of our water supply.
Many of these distribution lines for water
are near sewer lines, which would also be broken,
so now you have a situation where contaminants
are potentially getting into the water supply.
Narrator: Experts say you should keep
at least a two-week supply of water in your home.
As the ground shakes and sediments shift,
there will be landslides throughout Ventura
and Western Los Angeles County.
Brandenberg: There could be thousands of landslides.
There have been earthquakes that have produced thousands.
Landslides definitely can cause fatalities, property damage.
We have a lot of people who live up in the hills. Right?
So that's the location where you would be likely
to see landslides affecting people.
Narrator: And finally, the big one
will severely impact the economy.
Major transportation networks, like highways and railways,
could be unusable for weeks and even months.
Brandenberg: Some bridges may not be passable
after an earthquake.
We've had bridges collapse during past earthquakes.
Stewart: You might start seeing
key industries leave, population loss,
and this could have, you know,
devastating long-term impacts for the region.
Narrator: The estimated financial cost
of the big one is a whopping $200 billion,
with $33 billion in building damages
and $50 billion in lost economic activity.
This all sounds pretty bad, but keep in mind
that this is based off of a worst-case scenario.
The true impact of a major earthquake
is based on a range of unknowable factors.
Also, smaller earthquakes on faults
directly beneath major population centers
are a serious concern.
Vidale: But the worst-case earthquakes
are hard to predict.
You know, that earthquake in Japan in 2011,
their cost almost entirely came
because their nuclear power plant melted down.
It's very hard to predict what's gonna fail
in a big earthquake.
Narrator: So, how can Californians
prepare for the big one?
Brandenberg: Really have a plan in place.
You know, where are you going to meet?
What are you going to do?
Have water ready.
I have a 55-gallon drum full of water.
There's some chemical additive I put in it
so it's potable for five years.
Fifty-five gallons is the right amount for my...
I have a family of four.
That'll last us for two weeks.
Canned food.
You know, you have to be ready.
I would say it's best just to plan
to stay sort of where you are.
Getting out of LA is bad enough
without an earthquake, right?
Traffic's already terrible.
If roads are closed and people are all trying to leave,
it's gonna really be bad.