This is rather tangential, but your story just solved a minor mystery: the mud hot springs at Guanziling, Taiwan, where I'll be heading in two weeks, advertise themselves as one of only three in the world. Number two is Kagoshima, Japan (famously right next to the slumbering Sakurajima volcano), and now I know that number three, vaguely glossed as "Sicily" on said advertisement, is Vulcano!