An earthquake swarm - more than 140 little shakers centered around California's Salton Sea - has scientists worried that all that activity may mean a major quake is just around the corner.
Now word out of Caltech is that earthquakes can start shaking a lot deeper under the earth's surface than we thought.
And that means when the Big One finally does hit, it could be even bigger than we've ever feared.
Asaf Inbal, a researcher at the Seismology Lab at Caltech joined Take Two to explain.
Click on the blue button to listen to the interview