I wan't thinking so much in terms of eruptions. I was just wondering if there'd been any harmonic tremors, which can indicate magma moving if I understand correctly?
Beats me; that can only be picked up by seismographs literally on top of the volcano.
I don't know if any of the Iwo Jima ones are avaliable on-line and if they'd even be close enough to the submarine eruption to do so.