A flurry of small earthquakes rumbling near the Mammoth Mountain Volcano, have been categorized as "volcanic unrest" by the United States Geological Survey. Nearly three dozen earthquakes ranging from magnitude 2.6 to 3.8 have swarmed the area, northeast of Fresno, California, over the last two days.
Earthquake swarms in this region are not uncommon. David Shelly, a seismologist with California Volcano Observatory, said this swarm is "bigger than we've seen recently, but normal in the area."