New research shows the Hawaiian mantle plume has gotten hotter by about 250°C (480°F) over the past 47 million years. New research shows the Hawaiian mantle plume has gotten hotter by about 250°C (480°F) over the past 47 million years. Researchers also found that heat surges produced the two largest volcanoes along the Northwestern and Main Hawaiian Island chain. By examining olivine basalts from 16 volcanoes, the researchers assessed four testable causes, including changes in lithosphere thickness, magma source composition, rate of the Pacific plate movement and plume temperature. “It was a major surprise to find such a strong, direct correlation between mantle temperatures and volcano size,” said Garcia.