Earth’s rigid, brittle lithosphere is broken into seven major plates, as well as many minor plates, which ride along atop a ductile layer of the upper mantle called the asthenosphere. For all we know about Earth’s cracked outer shell, however, a clear picture of the lithosphere-asthenosphere boundary at the bottom of the plates has proved elusive. Now, new research using explosives to image the oceanic plate dipping beneath New Zealand’s North Island is helping to blast away some of the uncertainty about this boundary by giving scientists a sharper look at a piece of the planet’s tectonic underbelly.