The big one is referring to the massive earthquake that is supposedly going to happen in California in the near future and the supervolcano that's sitting under Yellowstone park that has the ability to wipe half the U.S off the map .
"The Big One" has been "a year away" for the past couple decades. At this point I'm just like, when it happens, it happens. I'm not about to stand around on my tip toes every day stressing over whether or not it's gonna come. Just live your life and remember to duck under that dining room table when you feel the ground shake sistrens.
It's definitely not happening in our lifetime but if it did happen, I'm ready to ride out the worse when the volcanic ash from the Supervolcano blocks out our sun for years and years, changing the earth's core temperature. Killing millions of humans and animals.