Fine structure of an oceanic crustal section near the East Pacific Rise

Abstract

In this study we model synthetically a complete seismic profile of roughly 20-m.y.-old crust located to the west of the East Pacific Rise, 3.37S, 114.13W. The results indicate a rather strong velocity gradient below the sediments with little evidence of layering in the upper crust and a slightly dipping oceanic layer. The crust-to-mantle transition zone appears sharp providing a relatively good wave guide for multiple Moho reflections which are modeled synthetically to further test the usefulness of a layered earth model in explaining entire seismograms. The mantle head waves decay abruptly near 50 km which can be explained by the onset of a low-velocity zone in the upper mantle at about a depth of 12 km below the ocean surface.