The U.S. Geological Service measured four quakes Wednesday night of magnitude 3.0 or greater, including a 3.6 magnitude temblor, a 3.5 and a 3.4. They all occurred within 40 minutes.
Kate Hutton, a California Institute of Technology seismologist, said swarms are typical in the area. She said that swarms usually occur for a few days, but it's impossible to know if the peak will come at the beginning, middle or end.
At the same time, Hutton said, the cluster of quakes doesn't mean there is a bigger one coming.