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Ulviyya Poladova

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A team of American and French seismologists has concluded that the massive earthquake that struck Japan in 2011 caused the entire country to shift approximately 5-6 millimeters eastward, AzerNEWS reports.

According to a study published in the scientific journal Science, seismic waves generated by the earthquake traveled all the way to Earth's core, reflected back toward the surface, and triggered movements in the tectonic plates beneath Japan.

"We found that after the extremely powerful earthquake that occurred off the coast of Honshu in March 2011, virtually all of Japan underwent an unusual displacement," the researchers noted.

The discovery was made by a team led by Pak Sonyeon, an associate professor at University of Chicago. Scientists analyzed data collected from thousands of seismic monitoring stations and a vast network of high-precision GPS sensors operating across Japan during the disaster.

Researchers observed that multiple tectonic plates began moving simultaneously about 13 minutes after the main earthquake struck. At that moment, seismic stations detected an unusual wave of displacement traveling from west to east across the country.

The study suggests that these movements were caused by seismic waves from the initial quake reaching Earth's core within minutes, bouncing back, and returning to the surface. The reflected waves then activated boundaries between several tectonic plates, including the Pacific, Okhotsk, and Eurasian plates, leading to sudden shifts in their positions.

According to the researchers, this mechanism had not previously been considered in seismic hazard assessments. The findings suggest that so-called "mega-earthquakes" may be capable of triggering additional tectonic movements through interactions involving Earth's core, potentially influencing seismic activity over much larger areas than previously understood.