Molten magma can cruise at high speeds from deep in the Earth to the surface, triggering volcanic eruptions. The discovery suggests that advance warning of an eruption might come from monitoring seismic action deeper in the crust than scientists usually look.
The new analysis, published in the Aug. 1 Nature, looked at the distribution of minerals and elements in ash from the 1963–65 eruption of Costa Rica’s Irazú volcano. When scientists Philipp Ruprecht and Terry Plank of Columbia University’s Lamont-Doherty Earth Observatory examined tiny crystals of the mineral olivine, they saw much more nickel than the researchers expected. That suggests that some of volcano’s magma hadn’t been stewing near the surface, but instead came fresh from Earth’s mantle.
The researchers calculated that magma may flow up from the mantle at speeds of 80 meters per day, creating what they call a “highway from hell.” This activity probably fueled Irazú’s eruption. If the same sort of plumbing connects the mantle to the crust at other volcanoes, then keeping an eye on deep crust activity could provide clues to an impending eruption.