Big Data Imagery Shows Rock’s Important Role in Channeling Japan’s Earthquakes

AUSTIN, Texas — Using 20 years of seismic data processed by one of the world’s most powerful supercomputers, scientists have created the first full 3D visualization of a mountain-sized rock called Kumano Pluto buried in miles below the coast of southern Japan. They can now see that the rock could act as a lightning rod for megaquakes in the region, diverting tectonic energy to points along its sides where several of the region’s largest earthquakes have occurred.

The Kumano pluton in southern Japan appears as a red bulge (indicating dense rock) at the center of a new 3D visualization by the University of Texas at Austin. The pluton is large enough to interfere with the nearby Nankai subduction zone and earthquakes in the region. Credit: Adrien Arnulf [Video] Nankai Subduction Zone 3D Model

Scientists have known about the pluton for years, but knew only small portions of it. Thanks to new research by an international team of scientists led by the University of Texas at Austin, researchers now have a comprehensive view of subterranean formation and its effects on the tectonics of the region.

The results will provide essential information for a major new project funded by the Japanese government to determine if another major earthquake is brewing in the Nankai subduction zone, where the pluton is located, said Shuichi Kodaira, director of the Japan Agency for Marine and Earth Sciences. and Technology and co-author of the study published on February 3 in the journal nature geoscience.

“We can’t predict exactly when, where, or how big future earthquakes will be, but by combining our model with monitoring data, we can start estimating processes in the near future,” Kodaira said. who was among the scientists who first spotted signs of Kumano Pluto in 2006. “This will provide very important data for the Japanese public to prepare for the next big earthquake.”

Simple map of Japan.  A shaded blue rectangle covers just under half of the bottom left.  The Nankai subduction zone is marked with an east-west line south of Japan.  The Kumano pluton is marked midway along the south coast, just north of the subduction zone.
The Kumano pluton is located in southern Japan, near the Nankai subduction zone. A research team led by the University of Texas at Austin compiled seismic data to create a 3D model of the Earth beneath the study area. Credit: UT Jackson School of Geosciences

The full extent of the Kumano Pluton has been revealed using UT’s Texas Advanced Computing Center’s LoneStar5 supercomputer to collate 20 years of seismic data into a single high-definition 3D model.

“The fact that we can make such an important discovery in an already well-studied area is, I think, indicative of what may await us in less well-monitored places,” said Adrien Arnulf, assistant research professor at the University. . of the Texas Institute for Geophysics and lead author of the study.

The model shows the region around the Nankai subduction zone, with the earth’s crust bending under the weight of the pluton. In another unexpected find, the pluton was seen diverting buried groundwater into the Earth’s interior. The researchers believe that the pluton’s interference with the larger subduction zone influences the tectonic forces that cause the earthquakes.

Seismic imaging uses sound waves to create images of the earth’s subsoil. Over the years, Japan’s extensive sensor network has collected millions of seismic records from thousands of locations along the Nankai Subduction Zone. Arnulf and his collaborators compiled the massive amounts of information into a single dataset and turned it into a 3D model with the help of LoneStar5.

A wireframe map of southern Japan showing masses of colored lines connecting seismic events scattered across the map with a handful of sensors.
A visual map of the data used in the UT-led study to recreate the Earth beneath southern Japan. To build a 3D model, scientists used Japan’s earthquake monitoring sensor network (red symbols) to trace seismic shock waves (colored ray paths) to their source (blue symbols) and extract information on the surrounding geology. Compiled with help from the Frontera supercomputer at UT’s Texas Advanced Computing Center, this is the largest seismic dataset ever created – only 2% is shown here. Credit: Adrien Arnulf/ UT Jackson School of Geosciences. [Video] UT is at the head of the largest seismic dataset ever created: 3D ray paths and Nankai data sources

As well as shedding light on how the Pluto can influence how and where earthquakes occur, the study is a major demonstration of how big data could revolutionize earthquake science. Arnulf plans to use the same methods to create regional scale images in other regions, such as northeast Japan, New Zealand and Cascadia in the US Pacific Northwest – all of which have subduction zones known to host Earth’s largest earthquakes.

The research was funded by the US National Science Foundation. Additional co-authors include scientists from the Scripps Institution of Oceanography at the University of California, San Diego. UTIG is a research unit of the UT Jackson School of Geosciences.

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