Sorry Petra, I was reading your post regarding triggering from Etna when we got
word of the earthquake in Tennessee, so I didn't get around to answering you at
the time.
The two events are less than 700 km apart, so triggering is a definite possibility,
although volcanic events usually release regional stress rather than adding to it -
the volcanic bulge is removed relaxing local and regional strain.
My suspicion is that the intensification of the Etna eruption, the new Eruption
of Mayon and the Aegean Sea earthquake yesterday and today are related to
the global effects of the geomagnetic storm yesterday. This was the largest
storm in more than a month, and such storms are often associated with increased
volcanism.

The Aegean Sea earthquake runs along a fault which is approximately
N/S. The Mb 4.6 foreshock on 25 July occurred at the northernmost end
of the rupture. A Mw 6.3 will rupture a fault length of 25-50 km. In general
there is no additional seismicity on the region of the fault that has ruptured - the
fault plane. The aftershocks will concentrate off the fault plane and at the
ends of the rupture. Thus, there will often be two distinct groupings of
aftershocks as in this case - at either end of the rupture zone, this is where
the fault motion stopped and strain began. Kind of like when your car is
in an accident, the car stops, but the strain continues in the form of crumpled
metal moving out of the way.