They've given rise to indie band names and tales of death at sea, but could rogue waves—seemingly random ocean events that exceed 60 feet in height—actually be predictable? Not quite, Tim Janssen says, but he might be able to tell where they are the most likely to form.
Janssen, a professor of geosciences at San Francisco State University, found that under normal circumstances, about 3 waves in 10,000 summon enough fury to earn the moniker "rogue." But in "focal zones," areas where the ocean's energy concentrates in one place, that tally can rise tenfold to 3 in 1,000. There are plenty of places in the ocean where currents converge, and in some places a steep change in the depth of the ocean floor focuses the power of the water with even more intensity.
The best surfing beaches in the world feature some of this kind of geography; that's why their big waves are so reliable. So Janssen, a keen surfer, had a pet interest in this work. But there's the dark side, too—rogue waves are a threat to the shipping industry today, and not just the ghosts of lore. His work could map for shippers the places where rogue waves are the likeliest, and where they might be wise to avoid.
Leave it to science to unravel the mythology of the sea. But, as any seasoned sailor would say, you never know exactly what to expect from the ocean.