Yeah, the location really doesn't fit with a nuclear test. To drill down 10 miles is something you just cannot hide doing.
If it was only a subsurface burst, then they just opened a giant can of worms because even China would flip over a non-underground test.
Either way, nuclear detonations generate a completely different kind of waves that are clearly different than an earthquake. If it was a nuke, it would be very obvious, very quickly.