19499

Your article has a graphic that appears to show an area that lifted by up to 5 meters and a vaguely equal area that was depressed by up to 2 m. This suggests an average increase in the distance of mass from the center of Earth. Yet a researcher claims that Earth’s rotation time has decreased. What am I missing?

Bob Williams
Los Alamos, N.M.

The graph shows the vertical displacement of the seafloor, most of which occurred on the Burma tectonic plate. In some places, several kilometers beneath the seafloor, the India tectonic plate slid downward as much as 20 meters—a phenomenon detectable only by the immense quantities of energy it released .—S. Perkins