Earth's largest volcano hides below two tiny rocks

摘要

AN EXTINCT Hawaiian volcano called Pūhāhonu is the largest in the world, with a volume twice that of the next biggest contender. What's more, the lava that once erupted from this giant is the hottest recorded in the past 66 million years. "Puhahonu is the most massive volcano on Earth," says Michael Garcia at the University of Hawai'i at Manoa in Honolulu. At the surface, though, Puhahonu doesn't look like much: just a pair of barren, rocky outcrops in the sea hundreds of kilometres north-west of the main Hawaiian islands. Its Hawaiian name means "turtle surfacing for breath". Garcia and his colleagues surveyed Puhahonu in 2014 using sonar and gravity sensors, which can measure mass. They found it has a volume of 148,000 cubic kilometres. That dwarfs Mauna Loa, another Hawaiian volcano generally though to be the largest, which is only 74,000 km~3 - although it is still taller than Pūhāhonu.