This is what I'm wondering. Yesterday, a geologist living in Mogul suggested to me that the recent earthquakes there remind him of the 1970's earthquakes in Denver, which turned out to have been caused by water injection in the area - with the water lubricating the faults and causing the earthquakes. Read up on the Denver earthquakes here with additional references here and here [the latter two are abstracts only]. The amounts of injected water they are talking about for Denver sounds rather large, and the injection (and earthquakes) took place over a considerable period of time.
As Andrew has noted, the Mogul-Somersett earthquake swarm is unusual: it didn't start with a large earthquake and dwindle into aftershocks, and it hasn't reached any kind of climactic peak. Also, the earthquakes have all been shallow. At least one geologist living in Mogul has expressed concern that, with the large Somersett development or subdivision located relatively high on a ridge above the valley Mogul lies in (Mogul is adjacent to and somewhat elevated from the nearby Truckee River and its floodplain), water from landscape watering and from the golf course might be lubricating a possible northwest-trending fault - the Nevada Seismological Laboratory (NSL) has more information about the quakes and a couple maps.
It may be that there isn't enough water seeping into the ground from the hillsides above Mogul to cause these earthquakes, and Ken Smith and Glenn Biasi at the NSL have been busy trying to diminish local rumors about the quakes, including the definitely false one that the local mountain, Peavine, is a volcano (it's not, never has been). From the Reno Gazette-Journal [I suspect some quotation marks are missing, or the paragraphs are parsed strangely].
In other words, it sounds like a possibility, one that has not at all been confirmed. In the meantime, my former colleague (and a couple other geologists?) are trying to contact Mike Alger, the geologist and meteorologist for KTVN Channel 2 and the Reno Gazette-Journal in order to have this issue looked into.
What about golf courses?
Another question is whether golf courses in th area changed the way the water table impacts the geologic structure.
Earthquakes can follow when the water table is changed, Biasi said. A well-known example is Hoover Dam.
As the rocks have less pressure, they will slip, causing earthquakes.
"Did the golf course perhaps raise the water table and contribute to this?" Biasi said. "We don't think so because you have a river at the bottom [of the valley]."
"It set the water table very high already, so the golf course could not have raised it very far."
Landscape watering would contribute to the problem, he noted. They can't rule it out because they don't know how high the water table was before the [Somersett] development occurred, Biasi said.
"It's a real long shot, but one we don't have any date to comment on," Biasi said.