Today there were some small earthquakes in the mountains just above Hawthorne, Nevada. But over the past few days, there had been many.
Here is a great and interesting conspiracy blog about the earthquake swarm in Nevada. There is indeed good info on these kinds of blogs, if you know what to look for and are discerning.
Now hard science. From the Reno Seismological Lab: Here are some views from a seismogram in Hawthorne, Nevada that show normal waveforms, not harmonic. These waveforms for the most part look like some cracking is going on, possibly creating new dykes and sills. Perhaps, but I have read and heard that the research community is still debating whether this is tectonic or volcanic in nature.
The above site is full of solid information on the frequency of the earthquake, categorized by magnitude and number of events. What should be noted is that this particular page, the one given above, states that there have been thousands of earthquakes near Hawthorne, Nevada below the magnitude of 1.