This market will resolve yes if a volcanic eruption with a Volcanic Explosivity Index (https://en.wikipedia.org/wiki/Volcanic_explosivity_index) of 2 or greater is directly triggered by human activities by Jan. 1, 2100. Both accidental and purposeful activities that directly cause an eruption will count. Some examples of direct triggers could include drilling or a human-caused explosion. Indirect mechanisms, such as climate change increasing the chances of eruption (e.g., https://pubs.geoscienceworld.org/gsa/geology/article/46/1/47/521232/Climatic-control-on-Icelandic-volcanic-activity), do not count.

I will use a consensus of reputable sources (USGS, peer-reviewed journals) to determine the VEI of an eruption and whether it was directly caused by human activity.