On the electrical nature of the axial melt zone at 13°N on the East Pacific Rise

Abstract

The first controlled source electromagnetic experiment directly on a ridge, with the potential to identify the presence of an axial melt body beneath a fast-spreading center, was conducted at 13°N on the East Pacific Rise (EPR) in 1989. The results of modeling observed electric field amplitudes reveal that resistivities in the uppermost crust are very low (~1 Ωm). No evidence was found for a large conductive axial melt body with dimensions on the order of kilometers in the middle or upper crust. This picture is consistent with recently proposed models of a thin sill-like melt lens with across strike dimensions of no more than 1km and probably with smaller vertical extent. -from Authors