[WPOZZZ]

Fee simple means you own the land under your home be it a house, condo, apt, building or raw land. As for the lava land, I guess the people still own it, eventhough it is not usable anymore. There are some instances of accretion when the sand built up on the beaches, increasing people's property. In Hawaii, if you own beachfront property, you own up to the high water mark /high wash of the waves onto the beach. Imagine how some properties have grown with the lava spewing into the ocean. The state will try to tax that growth one day.