The basic way in which new ocean crust is generated at mid-ocean ridges has been clear for some years, but there are many unanswered questions about the details. Does, for instance, the deep mantle participate in the process? The MELT experiment, which involved laying arrays of instruments across the fastest spreading mid-ocean ridge system, the East Pacific Rise, was designed to find some answers. The results — both seismological and electromagnetic — are now emerging, and are testimony to the power of complementary data of this sort.
