Local Volcano maybe awaking

A “local” volcano may erupt in the near future causing some grief. While not in any danger from the actual eruption, the ash fallout will be the problem. It can produce prolonged power outages and the lots of grit in the air. I am working on contingency plans and can cover the basics. What I need to know is what are items or events that may be less obvious that I need to plan for that may not be limited to just IT problems and protection of equipment. In particular, what about offsite operation to run the business? What are the experiences from those that have gone through other types of natural disasters?