If California's San Ramon had to pick a theme song, it might be AC/DC's "You Shook Me All Night Long." That's because over the past two weeks, the Bay Area town has endured more than 400 earthquakes—408, to be exact, which averages out to more than one quake an hour, Popular Science reports. Since Monday alone, there have been 60 quake recordings, per the Los Angeles Times, though most have been so small that no one noticed (they're taking place about 5 or 6 miles underground, per the US Geological Survey). The largest one recorded was a 3.6-magnitude shaker on Oct. 19. These earthquake "swarms" aren't unusual in the Golden State, though they're more prevalent in other areas, including the regions near Mammoth Lakes and Imperial Valley, per the Times.
"The good news is that most of these earthquakes stay under magnitude 4," a USGS Earthquake Science Center spokeswoman tells the San Francisco Chronicle. The USGS also notes that these tiny tremors don't necessarily mean a havoc-wreaking seismic event is around the corner—experts say there's only a 7% chance of there being a quake of 6.7 magnitude or higher over the next three decades, the Chronicle notes—and that the current swarm could continue for a few more weeks before finally dying down. "I've not felt so many tremors in decades," a local tells NBC Bay Area. "My dog … [is] the first one to know a couple of seconds before." (A controversial NASA study warns that the LA area will be hit within a few years with a major quake.)