Not getting it straight

摘要

New oceanic crust is generated at mid-ocean ridges in conjunction with mantle upwelling, a process that was generally assumed to be symmetric beneath active ridges. But new seismic imaging data from the East Pacific Rise show that this is not the case: mantle upwelling is in fact skewed. This may be part of the explanation for the segmentation of oceanic spreading centres, and may explain why one part of the ridge is volcanically and hydrothermally active, while another lies dormant.