The Case of the Volcano Mystery (1997)

The girls receive a call from some miners of marshmallows that a snowball-throwing monster has been "terrorizing" them. The girls eventually find out that the "snow" is really ash, and the "monster" is actually a geologist warning them that an active volcano is not a safe place to work. (The trip to Jelly Island was about 1,759 miles from their attic)