1) This was too big to be a nuke unless it was the largest of thermonuclear weapons (of a size even the US no longer has in its arsenal).
2) It was 35 miles deep. Can't be a nuke.
3) Nuclear explosions and quakes, even of the same magnitude, are INSTANTLY and easily distinguished on all seismographs. NEIC wouldn't have listed it as an earthquake otherwise.
"Nuclear explosions and quakes, even of the same magnitude, are INSTANTLY and easily distinguished on all seismographs."
Definitely NOT true.
The evaluation process cannot be done "instantly", is definitely not "easy", and definitely cannot be done on "all seismographs". In many cases, it is easy to classify as "definite earthquake", but classifying as "nuclear explosion" is much more difficult.