In the past month, parts of Reno, Nevada, have experienced a total of 274 known earthquakes. But if you’re surprised you haven’t heard about them by now, consider that the vast majority of those have been truly tiny tremors—just five of those quakes have been stronger than a magnitude 2.0, which means they’ve mostly been too gentle to feel. Some have even been so tiny that seismological networks haven’t even alerted scientists there has been a quake. Instead, they’ve pored through data to identify the small quivers.

According to Ken Smith, an earth scientist at the University of Nevada Reno’s Nevada Seismological Laboratory, the swarm kicked off on December 18, then quieted down until January 12. Then seismological activity picked back up and has continued since, although in the past day or so the tremors have slowed down again. “Things are starting to cool off a little bit, so that’s good news,” Smith told Newsweek. CONTINUE