Mountain-Sized Rock Beneath Japan May Act as Magnet for Mega Earthquakes

A massive igneous rock underneath the coast of southern Japan could possibly be serving as a magnet or lightning rod for megaquakes. According to a new 3D image of the Kumano Pluton, tectonic energy from megaquakes appears to be channeled to a number of spots along its side. 

Large-scale earthquakes in the area may be predicted more accurately, and scientists may learn more about how these igneous bodies interact with the Earth's crust.

(Photo : BANARAS KHAN/AFP via Getty Images)

Predicting the Impact of Megaquakes

Geophysicist Shuichi Kodaira of the Japan Agency for Marine-Earth Science and Technology in Japan believes that scientists cannot predict exactly when, where, or how large future earthquakes will be, but by merging models with monitoring data, they may begin to estimate near-future processes.

According to Kodaira, this approach will help the Japanese population prepare for the next major earthquake. In 2006, the first hints of the Kumano Pluton were made public. It is an igneous rock intrusion known as a pluton, a big block of rock that moves underground and cools and hardens over time. 

The Nankai subduction zone, where one tectonic plate slips beneath the edge of another, is characterized by high earthquakes and volcanic activity, according to Science Alert.

Seismic imaging revealed that there was something of a different density to the surrounding rock. The plutonic nature of the chunk was discovered through numerical calculations. 

However, the full scope of the problem remained unknown. Scientists have now plotted the whole Kumano Pluton using seismic data gathered from the Nankai subduction zone over the past two decades. 

Also Read: 8 Most Disastrous and Deadliest Earthquakes From the Last Decade

Collection of Seismic Data 

Despite the destructive nature of quakes, it can still be a tremendous instrument. Quakes are a truly wonderful phenomenon. They spread out from their source, bouncing across the globe, and reverberating throughout the universe. 

In order to map things that humans can't see, seismologists use the way seismic waves move through and reflect off different materials.

To construct the largest seismic data collection ever assembled, researchers compiled millions of seismic recordings from Japan's network of earthquake sensors, as well as those from other scientific surveys, as per Daily Mail. 

On the LoneStar5 supercomputer at the University of Texas at Austin, a high-definition 3D model of the pluton was generated from the enormous quantity of data gathered by the researchers. It showed things researchers hadn't seen before, which was fascinating to behold.

(Photo : WILLIAM WEST/AFP via Getty Images)

Does Pluton Have Great Effects on Geometry and Tectonic Activity?

The model revealed that Earth's crust is buckling and bulging slightly above the pluton because of its weight. As the Earth's crust continues to bend, the pluton appears to be creating a channel for groundwater to reach the upper mantle below. Tectonic activity may potentially be influenced by Kumano Pluton's density and rigidity. 

In 1944 and 1946, massive earthquakes with magnitudes of more than 8 shook the sides of the pluton. Subducting slabs are extremely sensitive to structural changes, so it is likely that the pluton is altering the geometry and tectonic activity of the area. 

The researchers have hope that their discovery will spur further exploration of the depths beneath additional subduction zones. 

"The fact that we can make such a large discovery in an area that is already well studied is, I think, eye opening to what might await at places that are less well monitored," according to Adrien Arnulf, a geophysicist from the University of Texas Institute for Geophysics

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