Wadati

Wadati refers to Kiyoo Wadati, a Japanese seismologist whose work laid important foundations for the understanding of earthquake depth and subduction zones. His research contributed to the development of methods for determining the focal depth of earthquakes and to early evidence for deep seismicity beneath ocean trenches. The Wadati diagram, named for him, is a graphical method for estimating earthquake depth by analyzing the arrival times of P- and S-waves recorded at seismographs.

In the 1930s, Wadati identified a pattern of earthquake foci that extended from shallow to several hundred kilometers depth along inclined planes beneath subduction zones. Along with Hugo Benioff, he helped establish the concept of the Wadati-Benioff zone, the dipping seismic zone that marks the down-going slab in subduction systems. The recognition of such zones provided key empirical support for plate tectonics, showing that lithospheric slabs sink into the mantle and generate earthquakes at increasing depth.

Wadati's work thus contributed to a new understanding of global plate interactions and the dynamic processes shaping Earth's surface. His methods and the zones named after him remain standard references in seismology, geophysics, and studies of subduction zones.