A study published in Science says Japan moved about 5 to 6 millimeters east after the March 11, 2011, Tōhoku-Oki earthquake when a seismic wave traveled down to the boundary between Earth’s mantle and liquid outer core, reflected back to the surface and triggered movement across much of the country. The analysis, led by seismologist Sunyoung Park of the University of Chicago, links the shift to a core-reflected shear wave that returned roughly 13 to 15 minutes after the magnitude-9 main shock...

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