Well, it wasn't weird in the sense of being supernatural, but it was very strange at the time because I'd never seen anything like it. A high-fountaining episode at Pu`u `O`o had ended several hours before, and we were about to fly back to the observatory. Then we saw these cracks starting to open in the ground on the uprift side of the cone. We went to look, and the cracks were continuing to open ahead of us, so we followed along, with the ground splitting open at about the same pace that we were walking. This went on for several hundred meters.