ON 29 August 2005, as hurricane Katrina was rumbling towards New Orleans, a seismic hum more than 1000 times the strength of the average volcanic tremor was felt nearly 3000 kilometres away in southern California. Its source was the hurricane itself.
Hurricanes create large ocean waves, which send energy pulsing through the Earth as they pound the shoreline. To determine the power of Katrina’s seismic waves, Peter Gerstoft of the University of California, San Diego, and colleagues analysed the signals recorded by a network of 150 seismic stations in southern California just before Katrina hit the Louisiana coast. They used…
