Sometimes seismicity can surprise you. There has been a minor swarm of
earthquakes in the Yosemite Village area of California today. I expected the
area to be fairly seismic, but a search revealed it to be relatively non-seismic.
This is a rare swarm of events. Similar swarms have occurred
on only 5 previous occasions - on 11-14-1980; 9-7-1989; 7-15-1993;
11-27-1994 and 11-6-1995. Only one of these swarms contained
4 earthquakes of Ml>=1.8, the others all contained three such
events. There have been only 10 events of M>=3.0 within 20 km of these
epicenters near Yosemite Village since 1960 , the largest of which was a
Ml 3.3. The largest event in this area occurred on June 21, 1957 with Ml 4.6.

Here are the events:
(Time is U.T)

20MAY2001 01:13:45 37.7N 119.4W ML=1.9 NCSN SE of Yosemite Village, C
19MAY2001 17:22:54 37.7N 119.4W ML=1.9 NCSN ESE of Yosemite Village, CA 19MAY2001 19:18:29 37.7N 119.3W ML=2.1 NCSN ESE of Yosemite Village, CA

The largest (Ml 2.1) falls within the magnitude range of Petra and Don's prediction
for the area slightly to the east of this, a prediction which began today. That prediction
fell a few km shy of these events (it was for an area within 36 km of 37.5N 118.7W).
These events occurred about 60 km west of the predicted location. However, it
should be interesting to see if this seismicity migrates to the east into
the Mammoth Lakes region over the next several days.