Southern California hasn't had a big earthquake since 1857. Here's what would happen if a mega earthquake hit California.

California lies in an area of hot fault lines, which can cause catastrophic damage without warning.
Parts of San Andreas fault haven't ruptured in more than 200 years. This means it's due for a large-magnitude earthquake, commonly known as "The Big One".

Here are the predictions of experts about what could happen seconds, hours and days after the Big One hits West Coast.

Below is the transcript of the video.

Narrator: Since the 1970s, catastrophic earthquakes have been terrifying viewers on television. They can cause massive destruction to buildings or even entire cities. This is what you can expect if the West Coast gets hit by the massive earthquake.

Narrator: Ridgecrest, California was struck by a 6.4 magnitude earthquake on July 4, 2019 and then another 7.1 one day later. However, none of these are comparable to the long-awaited great one that scientists believe will finally shake the golden coast. What will it look like when it does finally hit? Experts predict that the big one will strike in seconds, hours and days.

Narrator: Experts can't predict when a quake might occur but they do know where it will be. California lies in the hot zone of faultlines, with the most famous being the San Andreas Fault.

John Vidale: California is prone to a variety of earthquakes. The earthquakes that strike the San Andreas Fault are the most dangerous.

Narrator: The San Andreas Fault bursts on average every 150 years. Over 200 years, the fault's southern sections have remained inactive.

Vidale: Since 1857, we haven't experienced a major earthquake in Southern California.

Narrator: We are due for a major shakeup. A 2008 federal report states that the most likely scenario involves a 7.8 magnitude earthquake, which would rupture 200-miles of fault along the southernmost portion.

Vidale: The ground is moved several times over 50 square miles. The power of a magnitude 7.8 earthquake probably has the same power as the entire state's annual power consumption. This is basically something that civilizations have difficulty creating, other than a nuclear blast.

Narrator: It will almost be impossible to stand if you are within the epicenter of an earthquake.

Vidale: Many people think they can run out of bed and out of their homes. This is a bad idea because we often see people with broken legs or people who have run through glass. As we say every time, duck, cover and hold is the best thing. Cover a piece of furniture. Protect your chest and head.

Narrator: Buildings could fall during and immediately after shaking.

John Wallace: There are a lot of buildings built before 1980. These buildings are vulnerable to damage or collapse.

Narrator: This time-lapse video shows how building components would withstand a high-magnitude seismic event.

Wallace: The San Andreas will cause long-period shaking that could be very destructive to tall buildings in Los Angeles, Century City, Long Beach, Long Beach, etc. The connections in older steel buildings are not designed to withstand the highest forces.

Narrator: While unreinforced structures tend to be the most stable, even code-compliant buildings could collapse.

John Stewart: Despite its minimum requirements, the building code does not guarantee that the building can be serviceable in an earthquake. It is not intended to kill anyone. It's supposed to not kill anyone.

Narrator: Ten steel high-rises can collapse, and five of them could be completely destroyed. The earthquake would not cause a tsunami despite what Hollywood would have you believe.

Vidale: A tsunami is created when the ocean floor moves. Since most of the San Andreas are on land, there might be some waves from an earthquake. However, nothing that could be considered dangerous.

Narrator: A quake could cause the death of approximately 1,800 people, and more than 50,000 injuries. Fires are the most likely cause of death, with people potentially dying from falling debris or collapsed structures.

Vidale: Fire has always been the greatest hazard of earthquakes. In 1906, there were approximately 3,000 to 4,000 people who were caught up in the tsunami of fire that swept through the capital.

Narrator: The economic and infrastructure will be ravaged by the effects of the large one.

Scott Brandenberg: The infrastructure beneath our buildings and streets is complex. It could be destroyed and many of the basic services we depend on every day will be lost. Water, electricity, and being able to drive wherever you need to.

Narrator: 39 oil and gas pipelines cross the San Andreas Fault. This could cause high-pressure gas lines to burst, releasing gas into air and potentially igniting deadly explosions.

Stewart: If natural-gas lines rupture, you can set fire to them.

Narrator: After the fires have died out, the most important concern in an earthquake is the availability of fresh water. All major aqueduct networks which pump water into Southern California cross the San Andreas Fault. They could be severely damaged.

Stewart: Without the waterlines that bring in the imported water, we wouldn't be here. They travel through tunnels and cross aqueducts at the surface. These lines would burst, and we would lose 60% of our water supply. Many of these water distribution lines are located near the sewer lines which could also be damaged. This creates a situation in which contaminants can get into the water supply.


Narrator: Landslides will occur in Ventura County and Western Los Angeles County as sediments shift and the ground shakes.

Brandenberg: It is possible to have thousands of landslides. Many thousands of people have died in earthquakes. There are many ways that land slides can result in property and fatalities. Many people live in the hills. You get the idea? This is the area where you are most likely to witness landslides that affect people.

Narrator: The big one will have a devastating impact on the economy. Major transportation networks like railways and highways could be out of service for several weeks or even months.

Brandenberg: Bridges might not be safe after an earthquake. We've had bridges collapse during past earthquakes.

Stewart: It is possible that you will start to see key industries leaving, as well as population loss. This could have devastating long-term effects for the region.

Narrator: It is estimated that the huge one will cost $200 billion. There will be $33 billion of building damage and $50 billion lost economic activity. Although this sounds terrible, it is only a worst-case scenario. A range of unknown factors can affect the true impact of major earthquakes. Smaller earthquakes that strike faults below major populations centers are also a concern.

Vidale: However, the worst-case earthquakes can be hard to predict. Their nuclear power plant collapsed, and they were almost completely liable for the 2011 earthquake in Japan. It is difficult to predict the outcome of a large earthquake.


Brandenberg: Have a plan. What are your plans? What are you going do? Get water ready. I have a 55-gallon drum of water. It has a chemical additive that I added to it to make it potable for five year. My... There are four of us. This will last us for at least two weeks. Canned food. It's important to be prepared. It's better to just plan to stay where you are. Los Angeles is already bad enough without an earthquake. Traffic is already horrible. It's going to be really bad if roads are shut down and people try to get away.

NOTE FROM THE EDITOR: This video was first published in August 2019.