Researchers try to map out Hawaii's cataclysmic future

Tsunamis are inevitable in the islands but there's usually plenty of warning

On a map of the Big Island, Gerard Fryer can put his finger on the place where Hawaii as we know it stands to change forever.

In South Kona, between Kealakekua Bay and South Point, the coast arcs westward from Mauna Loa's southwest rift zone. Around 120,000 years ago, says Fryer, the coastal shelf collapsed into the ocean, creating a cataclysmic megatsunami that washed over the Hawaiian Islands, penetrating up to four miles inland and a third of a mile high.