Don --
Looks to me like that area responds quite efficiently to geomagnetic/
solar effects. Of course, we had a strong geomagnetic storm several
days ago and an X-flare the day before that.
The event on 24 April, 1984 also was associated with an X-flare which
occurred that morning about half a day before the Morgan Hill earthquake.
This was followed about the time of the earthquake by an extraordinary
X13 flare, the strongest recorded between July 11, 1978 and March 6, 1989
when a X15 flare occurred. Two more flares of about the same size also
occurred in 1989 - an X20 on August 16, and on Oct 19, 1989
the next X13 flare occurre - the same day as the Loma Prieta
earthquake.
The Coyote Lake earthquakes of Aug 6, 1979 followed on the heels of
strong geomagnetic storms on Aug. 1, and Aug 6, 1979. The storm
on Aug 6 started at 09:00 UT and continued through 21:00 UT at high
levels. The Coyote Lake earthquake occurred in the middle of this
geomagnetic storm at 17:05 UT.

Looks to me like the current swarm is telling us something about
earthquake triggering in the area.