I haven't tracked down the waveform signatures. One of my co-workers specializes in identifying the difference between normal seismic waveforms and nukes. That information would sort whether the speculation was valid.
There is a video circulating of an object that dropped in the water just seconds before the eruption. There is speculation that it was a nuke weapon dropped on top of the volcano. The 10MT estimate is for the weapon,
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Nuclear weapon? Right! Most likely a seismic package.
If it was a nuke, then there would be noticeable radioactivity reported everywhere.
Tinfoil is on sale nationwide.