A groundbreaking new research in the world of science has revealed for the first time how processes thousands of kilometers below the ground directly affect tectonic movements on the earth. Seismologists examining the devastating Tohoku Earthquake that occurred in Japan in 2011 discovered that seismic waves reflected from the earth’s core permanently shifted the Japanese mainland eastward.
This study, published in the journal Solid Earth, was recorded as the first research in history to prove this mysterious dynamic between the earth’s core and tectonic plates.
Here are the details of that extraordinary natural event that moved billions of tons of giant plates:
THE MYSTERY OF “SCS” WAVES
The 9.1 magnitude Tohoku earthquake in 2011 occurred when the Pacific Plate suddenly plunged under the Okhotsk Plate, which carries Japan (a subduction zone). This massive rupture produced very powerful seismic waves that spread across the world.
The international research team, led by University of Chicago seismologist Sunyoung Park, focused on one particular of these earthquake waves: the ScS wave.
-Journey: These shear (S) waves, released downwards from the earth at the time of the earthquake, passed through the earth’s mantle and reached the liquid outer core boundary (CMB) at a depth of approximately 2,900 kilometers.
-Reflection: Just like a sound wave hitting a hard wall, it reflected from this barrier and climbed back up towards the earth.
HOW DID THE PERMANENT SHIFT OCCUR?
Under normal circumstances, a seismic wave creates an elastic ripple as it passes through an area; After the wave passes, the ground returns to its original position. But in Tohoku the situation was completely different.
Minutes after the earthquake’s main shock, ScS waves reflected from the core reached back to Japan. At that time, the intersection of two tectonic plates (plate boundary) was already on the verge of breaking and locked due to the enormous stress created by the main earthquake.
The ScS wave returning from the nucleus threw a “light shoulder” into this locked region in a timely and synchronized manner. As a result of this dynamic triggering created by the wave:
-Frictional resistance at the plate boundary was broken momentarily.
-A large swath of Japan has permanently shifted 5 to 6 millimeters eastward from its starting position.
This millimetric shift may sound small; However, since it spread across a huge plate boundary, it caused the release of energy equivalent to a 7.5 magnitude earthquake when calculated holistically. The reason why no new tremors were felt on the surface was that this energy was distributed synchronously over a very wide area, rather than breaking at a single point.
ILLUSION OR REALITY?
Scientists initially thought that this permanent displacement of 5-6 millimeters was a data error (noise) or the result of a massive landslide under the sea. However, these doubts were eliminated thanks to Japan’s world-famous advanced earth observation network GEONET (GPS stations).
The research team eliminated all alternative scenarios using AI-powered data simulations and computer models. The findings were clear:
-Global Detection: The impact of the wave was so great that it exceeded the limits of traditional seismometers and was clearly recorded not only on GPS in Japan but even on observation stations in China.
-Synchronization: It has been proven chronometrically that the permanent shift occurs at exactly the second that the ScS waves reach the surface.
A NEW ERA IN THE HISTORY OF SEISMOLOGY
This discovery may cause earth science (geophysics) books to be rewritten. Until now, it was not thought that the waves reflected from the earth’s core had a mechanical power that could permanently move the tectonic plates on the earth.
Experts state that similar core reflections should be monitored in large earthquakes that may occur in the future. Completely unraveling this mechanism could play a revolutionary role in earthquake risk analyzes and early warning systems by enabling us to understand which dynamic factors trigger locked fault lines.
