
A seismic wave from Japan’s 2011 magnitude-9 earthquake travelled nearly 2,900 kilometres down to Earth’s core, bounced back to the surface 13 minutes later, and shifted the entire country eastward by roughly six millimetres at the same instant — in the first observation of its kind ever recorded
For 15 years after the 2011 Tohoku-Oki earthquake — among the most thoroughly instrumented natural disasters in history — a small anomaly in the GPS data sat unresolved in the archives.



