My inbox has been flooded with these earthquakes. I had set my trigger to M4.0 in the US, just to catch the next OK significant earthquake, but it's all this Nevada crap.
That's a 10 km square. Apparently these things are quite common in the region, always topping in a few weeks with some M5's. The dimensions limit the magnitude. I've come to the conclusion that such swarms are always the result of water bursting through a barrier. The small size is an indicator. As well, if they had decent seismometer coverage, and looked carefully, they would find identical couplets which are characteristic of fluid flow. I doubt the coverage is any good here.