
It looks like volcanoes do not correlate with other events, including earthquakes (which disproves a part of my original hypothesis). But there seem to be a small increase in the number of eruptions every 58 years.
This is probably because two hurricane cycles in every sunspot cycle can effectively cancel each other out.
Therefore, I separated years where it seems to be a correlation between hurricanes and sunspots from those where it seems to be an anticorrelation:
Correlation coefficients for years 19661973, 19781982, 19861993, 19982002 (where it seems to be a correlation):
Correlation coefficients for years 19731978, 19821986, 19931998 (where it seems to be an anticorrelation):
It looks like the separation of the hurricane data into two parts produced a good correlation of 0.49 (with the 1 year time lag) for the first set of data, but smaller anticorrelation, 0.35, for the second set of data (also with the 1 year time lag).