Whose work first explained how volcanoes form at subduction zones?

American geophysicists Harry Hess and Robert S. Dietz were key figures in explaining why volcanic arcs form above subduction zones. Their seafloor-spreading ideas showed that new oceanic crust is created at mid-ocean ridges and later sinks back into the mantle at trenches. As the subducting plate descends, it releases water and triggers melting above it, feeding volcanoes. This explained chains such as the Andes and the Japanese islands. Their work helped turn scattered observations into a coherent theory of Earth's moving plates.