There's a geothermal power plant that recently started fluid injection, since then the area has been shaking even more regularly. (Believe it or not
induced seismicity in such circumstances is a recognized phenomenon) But it's a very active region regardless of the power plant, and CA in general
has been pretty active today. There was just a 3.3 near Tres Pinos and earlier in the day a pretty good shaker in the San Bernardino area.