Topic: seismic imaging

Andreas Fichtner explains progress and obstacles in seismic imaging of Earth at regional and global scales. He discusses the evidence supporting three-dimensional maps of mantle plumes, continental interiors, mid-ocean ridges and large low-shear-velocity structures, and how improved methods increase confidence in the images.

Folarin Kolawole explains how continental lithosphere breaks apart, from distributed normal faulting to localized extension and eventual ocean-basin formation. Field observations, seismic imaging and rock mechanics help reveal the early stages of rifting. Examples connect active rifts with passive continental margins left by earlier breakup.