From what I understand, offering are put on top and they fall through. Periodically, a guardian comes up and buries the offerings in the base.
The lava flowed this far, but no further. The highway used to go through, but a lava flow 1983 destroyed the route. John Harvey Photo > Trips out of the Country > The Big Island of Hawaii > Volcano National Park > Us at the End of the Road
The surface of Kilauea Iki Crater has been pushed up places and some of the cracks emit warm air or moisture.