Seafloor features steered tsunamis

Tsunamis circled the globe after a magnitude 9.3 earthquake struck the Indian Ocean last Dec. 26 (see “Earthshaking Event,” in this week’s issue). However, those waves didn’t spread evenly, says Vasily Titov of the National Oceanic and Atmospheric Administration in Seattle. Computer models suggest that the largest waves (orange zones) initially moved perpendicular to the rupturing fault (black boxes in inset).