>>54244291Cinnabar Island had a volcano before it erupted and destroyed the town, and seeing how the Volcano only erupted in the past few years, it's likely the the dessert was named prior to the event. What's funny is Gen 1 lore repeatedly refers to the volcano on Cinnibar but you never see it in-game until it erupts in Gen 2.
They tried to Retcon in in Let's Go by implying it's simply always to the right, off-screen but is 100% there.