WOULD a volcano blow its top if it was called petite? Let鈥檚 hope not, because that鈥檚 the name given to some unusual volcanoes just discovered in the western Pacific. And they are changing our understanding of how volcanoes form.
Naoto Hirano at the Tokyo Institute of Technology, Japan, and colleagues discovered the volcanoes, which are between 0.005 and 1 cubic kilometre in size, near the underwater Japan Trench. The 鈥減etit-spot鈥� volcanoes are 1 to 8 million years old and defy conventional theories of volcanism. They don鈥檛 sit at tectonic plate boundaries nor at 鈥渉otspots鈥� of rapidly rising plumes from the boundary between Earth鈥檚 core and the mantle (Science, DOI: 10.1126/science.1128235).
The team thinks the mini volcanoes were created when cracks formed in the Earth鈥檚 crust during the bending of the north-western Pacific plate as it dives under the Kuril and Japan trenches, squeezing partially melted material from the upper mantle out of the cracks. 鈥淚 was unbelievably excited to discover this volcanism,鈥� Hirano says.
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