A new type of ocean wave has been found. It hugs the sea bed and constantly exchanges energy between the sea floor and the water just above it.
It was discovered by Cinna Lomnitz of the University of Mexico and US oceanographer Rhett Butler using data from a unique sea floor seismic observatory in the Pacific.
Professor Lomnitz was alerted to the possible existence of so-called coupled waves by the disastrous earthquake in Mexico City in 1985.
Destructive waves rippled through mud layers beneath the city causing many buildings to collapse. The waves found spreading through the oceans following earthquakes are similar.