Japan shifted position on the map after the March 11, 2011 earthquake, scientists uncover unknown seismic phenomenon

A new scientific study has highlighted a previously undiscovered phenomenon linked to the devastating earthquake that struck Japan on March 11, 2011.

The research, led by geophysicist Sunyoung Park of the University of Chicago, shows that around 15 minutes after the magnitude 9.0 earthquake, nearly all of Japan’s territory shifted permanently eastward.

At first, the movement of 5 to 6 millimeters was interpreted as an inaccuracy in GPS measurements. But after years of analysis, researchers concluded that it was not a technical error, but a previously unknown seismic phenomenon.

According to the study, the earthquake’s powerful waves penetrated all the way to the Earth’s core and then returned again toward the surface. This return caused a synchronized displacement across a very wide area, stretching from Hokkaido to Kyushu over a distance of more than 1,800 miles.

Scientists explain that it has long been known that seismic waves can reach the Earth’s core, but it was thought that their energy dissipated before returning to the Earth’s crust. The latest discovery shows that this energy is capable of returning and producing measurable movement at the surface.

Geophysicist Goran Ekstrom said that the 2011 earthquake had moved the island of Honshu approximately 20 centimeters eastward. Meanwhile, the newly discovered phenomenon, although smaller in impact, affected a much broader area and released energy comparable to a magnitude 7.5 earthquake.

The March 2011 earthquake continues to be considered the most powerful in Japan’s history. It triggered the catastrophic tsunami and the Fukushima nuclear crisis, while claiming the lives of around 20 thousand people.

According to the researchers, this new phenomenon represents a seismic risk that had not previously been included in assessments. Unlike traditional aftershocks, waves that descend to the Earth’s core and then return can be predicted, since the entire process lasts approximately 15 minutes.

Experts believe this discovery could contribute to a deeper understanding of how tectonic plates behave, as well as to improving seismic monitoring systems in the future.

“We still do not fully understand how tectonic ruptures work, and these observations give us another important piece of the puzzle,” said geophysicist Amanda Thomas of the University of California.