Interesting map to compare with:
https://www.meteoblue.com/en/weather-maps/?variable=cams_so2...
In New Zealand the high concentration area is just south of a few active volcano's so it seems that some of it on that map is probably natural causes.
And another one from NASA: https://earthobservatory.nasa.gov/images/36063/sulfur-dioxid...
Choice quote for others sourced from the first link:
>Whilst sulphur dioxide emissions are definitely associated with pollution from the mining of nickel these emissions that Dave and Margo have observed are far too extensive for this to be more than a partial explanation.
>It is simply much too large.
>Also of interest, the emissions are intermittent just as methane emissions are.
>One very reasonable hypothesis is that there have been geological changes which is leading to magma coming to the surface much as it did in the Permian extinction.