The Hawaiian-Emperor seamount chain spans almost four thousand miles from the Hawaiian Islands to the Detroit Seamount in the north Pacific. The 60 degree bend in the line of mostly undersea mountains and volcanic islands has puzzled scientists since it was first identified in the 1940s from the data of numerous echo sounding ships.
A team of scientists used the XSEDE to model and reconstruct the dynamics of Pacific plate motion that might explain the mountain chain bend.
Major findings.
The Pacific plate can change direction from the north to the west with the help of computer models, according to Michael Gurnis, professor of Geophysics at the California Institute of Technology.
He said that it has been a holy grail to figure out why the change happened. The study on the origins of the seamount chain was published in Nature Geoscience.
The team consisted of a post-doctoral scholar at Caltech, Dietmar Muller, and computational scientists from New York University and Argonne National Laboratory.
There are clues in the plate motion.
Understanding how the seamount chain reflects plate motions is dependent on the plate motion. The hot, weak rock of the mantle is the location of the giant tectonic plates.
One of the largest plates is the Pacific Plate. The return of the plates to the mantle created a 40 million square mile plate that is outlined by the mountains and volcanos of the Ring of Fire.
The volcanos of Hawaii and the Hawaiian-Emperor seamount chain were not caused by this process. Scientists theorize that the hottest rock on Earth travels upward through the mantle to create a volcanic hotspot. A trail of burn marks on a paper moved over a candle is what it is believed the seamount chain was created by.
The Pacific plate traveled north for 30 million years, as shown by the line of Emperor seamounts. Something strange happened about 50 million years ago. The Pacific plate apparently changed direction.
There may be an underlying physical reason why they would happen at the same time.
The Gordon Bell Prize was given prior to it.
He pointed to previous work using techniques such as adaptive mesh refinement on the dynamics of mantle convection, computational work that scales well to a large number of computers and earned the team spearheaded by Johann Rudi the Gordon Bell Prize in 2015.
Gurnis said that earlier work with Mu and others showed how the physics of the mantle could work, and that the plume could have stopped 50 million years ago.
We had a model that could explain the motion of the plume to the south, but we didn't have a model that explained how the plate could change its direction.
The team had to account for the faults at their boundaries but still allow the movement of plates.
Computational challenges.
The challenge of getting both of those pieces of physics computed at the same time meant that they needed computational methods that could handle huge changes in the mechanical properties from one plate to another.
The traditional ideas of plate motion didn't add up to enough force to pull the Pacific Plate to the west.
There was another idea in the literature, but it wasn't getting much attention.
There is a new factor.
The subduction zone in the Russian Far East was a new factor that was accounted for in the study. New plate tectonic reconstructions were built with these subduction zones.
They discovered that they could make the Pacific plate go to the north when they put the zones in the models. When the subduction ended, the Pacific plate moved to the west, slowly building up other subduction zones that provided more force to pull it.
It is a new hypothesis that is based on physics and will allow other scientists to see if it will hold up to further scrutiny.
Computational resources.
The National Science Foundation funded the study and gave Gurnis access to the Stampede2 supercomputer. He was given access to the most powerful supercomputer in the world, the Frontera system, at TACC.
Both XSEDE and Frontera are vital for our research.
He said that capability computing is essential and that they are spinning up larger projects with this collaboration.
Mysteries about the past and present Earth are the focus of this basic research.
When dealing with some of the most fundamental processes in the earth, it is important to figure out how they work.
There are new directions.
The interplay between domain science and applied work was highlighted.
Gurnis said that the adaptive mesh refinements can be applied to many pure and applied problems.
Gurnis said that they now have a way to move us in new directions. The Hawaiian-Emperor seamount problem was not on my mind when I started this project. New ideas and capabilities came forward after that. New science questions could arise suddenly. The basic phenomenon which governs some of the most important processes shaping the earth can be discovered by using the power of supercomputers.
More information: Jiashun Hu et al, Dynamics of the abrupt change in Pacific Plate motion around 50 million years ago, Nature Geoscience (2021). DOI: 10.1038/s41561-021-00862-6 Journal information: Nature Geoscience Citation: Hawaiian-Emperor undersea mystery revealed with supercomputers (2022, March 22) retrieved 22 March 2022 from https://phys.org/news/2022-03-hawaiian-emperor-undersea-mystery-revealed-supercomputers.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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