Shaken Beliefs: Seismic Lessons from Japan’s Tohoku Earthquake

Japan could well be called the cradle of seismology. It occupies one of Earth’s most precarious tectonic settings, at the nexus of four plates, and its written record of earthquakes extends back to 599 A.D., during the reign of Empress Suiko. Japanese seismologists of the early twentieth century made a number of significant contributions to geophysics, some of which anticipated plate-tectonic theory by decades. In 1899, several years after a powerful tsunami struck the Sanriku Coast, a man named Akitsune Imamura correctly inferred the type of fault slip (now called a megathrust event) that generates such waves. In the nineteen-twenties, another Japanese scientist, Kiyoo Wadati, collected seismic data that became critical to the development of the Richter scale and, eventually, the discovery of the process of subduction, in which old ocean crust sinks back into Earth’s mantle. Today, Japan spends more money per capita than any other country on earthquake research, engineering, and preparedness.