Supersonic @60K feet: how loud @ground?

Factual Questions
1

Inspired by this discussion of supersonic passenger transport.

Flying supersonic at low altitudes tends to cause problems for nearby ground-dwellers.

What about flying Mach 2 at 60K feet? How loud/destructive is the shock wave once it’s propagated 12 miles down to the ground? Is it just an annoyance, or is it enough to break windows and such?

2

The size and shape of the aircraft will have a lot to do with it. I heard sonic booms from a Space Shuttle at much higher than 60,000 feet, but they sounded like distant thunder.

3

Sound pressure decreases by 6 dB as the distance from the source is doubled.