The scientists used tremors from earthquakes to probe the inside of the planet just as sound waves allow doctors to look inside a mother's. The technique, a greatly refined version of earlier efforts, produced a surprisingly sharp image and yielded the first direct measurements of giant spouts of heat, called mantle plumes, that emanate from deep within the planet.

Mantle plumes are believed to cause island chains, such as the Hawaiian Islands and Iceland, when the Earth's crust passes over the column of heat. Although accepted by most scientists, the existence of mantle plumes has been fiercely contested by a minority of researchers in recent years.