• WARNING: Spoilers

    The film opens with a girl, Natalie (Morgan Griffin), driving along the cliffs of San Fernando Valley, 16 miles (25.75 km) north of Los Angeles, when suddenly a rock slide pushes the car, causing it to fall and then hang at the edge of a cliff. Moments later, Los Angeles Fire Department helicopter-pilot Chief Raymond "Ray" Gaines (Dwayne Johnson) and his other colleagues comes to rescue the girl trapped in the car. Ray safely rescues the girl moments before the car falls off the cliff.

    In CALTECH, Dr. Kim Park (Will Yun Lee) receives data of minor earthquakes in Falco, Nevada and shows it to his colleague and seismologist Lawrence Hayes (Paul Giamatti). The minor quakes measure 2.0 to 2.6. Hayes is curious about why such minor quakes can happen even where there are no faults in Nevada. Hayes and Park decide to go to Nevada to find out.

    While Ray is calling his daughter, Blake (Alexandra Daddario), for an upcoming trip to San Francisco, he receives divorce papers. Recently, he was divorced from his estranged wife Emma (Carla Gugino) and she is now with her new boyfriend Daniel Riddick (Ioan Gruffudd).

    Meanwhile, at the Hoover Dam, Park along with Hayes is now testing a magnetic pulse of quake. Suddenly, his device detects a spike pulse and then a stronger earthquake triggers. It measures 7.0 - highest ever recorded there. As the dam starts to break, Park struggles to escape while Hayes tells the people still on the dam to get off. Park now exits the dam facility, however when he sees a girl afraid to move on the breaking dam, he stops to grab her and carry her out. The girl is rescued but Park is impaled by a rod in his right foot. The dam completely crumbles and Park is killed. The disaster leads to the flooding of towns. The earthquake is the strongest and most destructive ever recorded in Nevada's history.

    Back in California, Ray arrives at his family's house to plan for their trip. But Ray is called back to work to rescue disaster victims in Nevada. Daniel and Blake drive in to San Francisco for a meeting. While Daniel is having a meeting, Blake meets an English guy named Ben Taylor (Hugo Johnstone-Burt) - having an interview - and his brother, Ollie (Art Parkinson).

    In CALTECH, the reporter, Serena (Archie Panjabi) arrives and wants to interview Hayes about what happen in Nevada. Hayes states that they didn't know there was any fault line there. He says that they should be able to predict an earthquake. One of his colleague interrupts Hayes and presents him with data showing the pulse rates detected along the entire San Andreas fault. The pulse rates are higher than Nevada. Hayes then explains to them why the earthquake triggered in Nevada even with no fault line: his theory is to draw a fault line near Nevada and it connects to the end of the fault boundary. Hayes predicts that the whole San Andreas might trigger.

    In Los Angeles, Emma is having a lunch with Daniel's sister, Susan, in a high rise restaurant. After some conversation with Susan, Emma answers a call from Ray, in the helicopter en route for maintenance. Ray apologizes to Emma for what he did the other day. Their phone conversation is interrupted by the strong earthquake. Emma tells Ray that they're having an earthquake and he also notices that the freeway is crumbling. Ray instructs Emma to get to the roof for rescue. According to the CALTECH, the first major earthquake peaked at 8.5 and later 9.1. Not only in Los Angeles, but the whole of California and the quake is heading to San Francisco where Blake and Daniel are.

    While the ensuing destructive earthquake hits, the people inside the building panic in terror; some are injured. Emma tells Susan to get to the roof, but she goes to the exit and is killed in a crumbling floor. Emma makes it to the roof, with the floor and the surrounding structures crumbling around her. Emma manages to recover and emerges from the rubble. Finally, Ray rescues Emma and they barely escape as the surrounding structures collapse. The whole city is now completely devastated.

    Meanwhile in San Francisco, after Ben's interview, Blake borrows Ollie's book to write her number in it for Ben to call her. Blake and Daniel are leaving the building parking lot when the earthquake hits. They manages to escape but the ceiling collapses and they become trapped. The debris crushes part of the car, trapping Blake's leg under the driver's seat. Daniel goes to get help. As Daniel calls for help, the debris falls near him and kills a security guard. Daneil flees in terror instead of saving Blake.

    However, Ben and Ollie are struggling to save Blake as the debris above her continues to press the roof. By using the jack to lift the debris, the driver's seat pushes away but Blake's leg is still stuck. Finally Ben pops the car tires lowering the car and they rescue her. The trio get out of the building as the aftershock continues. The trio decides to go to the electronic store to contact Ray.

    At the store, Blake finds a phone and she calls her parents telling them that she's okay. Also, she tells them that Daniel left her. This makes Emma angry and she leaves a nasty message on Daniel's voicemail. Ray advises Blake that they will need to get out immediately and to go to the Coit Tower as a rendezvous. Ray and Emma quickly head to San Francisco to save their daughter.

    Meanwhile, Daniel is walking through the crowd in the street when suddenly another strong earthquake hits. The structure over the crowd collapses. In order to save himself, Daniel steals the safe spot of one of someone else and the victim is swept away by the debris.

    When Ray and Emma are en route to the city, the helicopter's engine fails, forcing them to make a crash landing into a superstore in Bakersfield. As they try to steal a vehicle, which is already stolen, the thief aims a gun at Ray but Ray manages to subdue the perpetrator and they drive away.

    With the help of Serena, Hayes is able to warn the people through news coverage of a much bigger earthquake about to hit San Francisco. He tells the people of San Francisco to get out now because their lives depends on it.

    After Ray and Emma obtain the vehicle, they drive till they meet an elderly couple who warns them to stop - it is the now-opened San Andreas fault rendering the road impassable. They drive back to the old couple's home. The couple happens to own an airplane which Ray exchanges for the stolen car. Ray and Emma manage to fly the plane to San Francisco. While on the plane, Ray recaps what happen with their daughter, Mallory, who died in a rafting accident. Ray regrets he could not save his daughter. This the underlying reason Emma wants a divorce. Then they fly to San Francisco.

    Blake, Ben and Ollie, walk through the crowded streets to Coit Tower - the agreed on meeting place. However, it is already engulfed in flames so they change the plan by going to the highest ground which is Nob Hill in order to signal Blake's family.

    Ray and Emma make it to San Francisco but they cannot land the plane because the airport has a lot of cracks and scattered planes. Ray and Emma have no choice but to sky dive into the stadium leaving the plane to crash into the Pacific Ocean when it runs out of fuel.

    Meanwhile, Blake, Ben and Ollie are walking through the deserted street when the strong earthquake hits. The earthquake measures 9.6, the largest recorded in history. Blake and Ollie quickly get to the side of the street ... but Ben goes to the opposite side. The glass shards, coming from the building, cuts Ben's leg. The remaining still-standing structures are destroyed, the ground ruptures, suspension bridges crumble, etc. At the same time, Ray manages to tell other people people to move to safety on the other side of the stadium as the structure crashes down.

    After the earthquake, Blake carefully removes the glass shard from Ben's leg and then they move to the highest ground. Ray and Emma drive a boat to the city where they see Coit Tower is on fire. Ray knows that Blake has gone somewhere else. They notice that the water is receding quickly, which means a tsunami is about to hit the city. As the trio receives the tsunami warning from the radio, it is too late for them to head to the highest ground. So, the trio quickly heads to Daniel's unfinished building.

    Ray and Emma, in the boat (and many other boats), manage to drive into the giant tidal wave. They make it to the top just before the wave crests though they are almost hit by a cargo ship that is carried along by the tidal wave. Daniel, happens to be on the Golden Gate Bridge when the wave strikes. He is crushed by a falling shipping container from the overturned cargo ship. The cargo ship slices the Golden Gate Bridge in half and the tidal wave continues to race towards the city. Sadly, most of the people on the ground are swept away by water and debris.

    The trio is in now in the building when the tidal wave hits. Ray and Emma drive the boat through the devastated town looking for Blake. Blake and Ollie sees her parents riding in the boat but they don't see Blake. Ollie then uses the laser pointer that he obtained from the electronics store to attract Blake's parents' attention. Now the parents see them, but before they can save them, the building starts to sink into the ground. Blake is separated from the two brothers as they make it up to the next floor. Blake is now trapped inside as the water continues to rise. Ray manages to get to his daughter, but now the exits are jammed. Blake then seems to have drowned and Ray struggles to get her body out. As the building is going to collapse, Emma crashes through the window in the boat and they quickly get out as the building finally collapses.

    Once outside, Ray continues to try and then successfully revives Blake - reunited with her family. The two boys are also rescued. Later, the five make it to safety in Marin County. The family along with Ben and Ollie watch the sunset on the destroyed and radically altered geography of the San Francisco Bay Area and they talk about the future. They also see an American flag is waving over the now-destroyed Golden Gate Bridge.