Disaster-plagued cities. Hellish landscapes. Post-apocalyptic society. It’s just your average day in California. With one special exception: A 9.6 earthquake has rippled up and down the state, unleashing unimaginable devastation. That’s the plot of San Andreas—but could any of this happen in real life? Let’s ask SCIENCE.

Among the many luminaries invited to preview the film was Dr. Lucy Jones, the USGS seismologist who recently took me on a walk along the Hollywood Fault, which runs just a block from the theater where San Andreas premiered. She now works for the City of LA, which she calls “the most interesting geological place in the US”—an understatement as oversized as Dwayne Johnson’s thighs.

After getting her photo taken with The Rock on the red carpet, Jones took her seat and proceeded to fact-check the film, posting her thoughts live via Twitter. Here are some of her criticisms of the movie. Warning: Mild, 3.0-magnitude spoilers.

Her final verdict on the film itself? “Better than I thought it would be.” For a more thorough explanation of what could actually happen when the Big One hits (and it IS coming), Jones recommends this report. Whatever you do, don’t believe what you see on Dutch YouTube videos.