Research led by the University of Cambridge succeeded in obtaining a detailed picture of a painting for the first time. Unusual rock structure in the border region with the Earth’s core, about 3,000 kilometers below the surface. Located in a place where its presence was not expected, this solid body could explain the existence of volcanoes like those in Hawaii and others scattered around the Earth.
This mysterious rock field, Located just below the Hawaiian IslandsIt is one of the few ‘ultra-low velocity zones’ discovered – so called because seismic waves slow down as they pass through – has been discovered.
Research published this week, Nature CommunicationHe was the first to reveal in detail the complex internal variability of one of these regions, thus shedding light on the landscape of Earth’s deep interior and the processes that operate within it.
“Of all the intra-earth features, these are the most fascinating and complex. We now have the first tangible evidence of its interior structure: is a true milestone in deep earth seismologysaid lead author Zhi Li, a student in Cambridge’s Earth Sciences Department.
The Earth’s interior has layers that are structured like onions: a core of iron and nickel at the center is surrounded by a thick layer known as the mantle, and above that is a thin outer layer – the crust in which we live. . . .
Although the mantle is solid rock, it is hot enough to flow extremely slowly. These internal convection currents feed heat to the surface, driving the movement of tectonic plates and also fueling volcanic eruptions.
Scientists use seismic waves to see what’s under the Earth’s surface; echoes and shadows from these waves reveal radar-like images of the deep interior topography. But until recently, images of structures at the core-mantle boundary, a major area of ​​interest for studying our planet’s internal heat flow, were too grainy, poorly defined, and difficult to interpret.
Now, the researchers have used the latest numerical modeling methods. thus, it can reveal much higher resolution structures at the boundary between the core and the mantle.
“By leveraging wave symmetries that were not noticed or used before, we are really pushing the boundaries of modern high-performance computing for elastodynamic simulations,” said Kuangdai Leng, who developed the methods while at Oxford University.
A large iron bag outside the core
They observed a 40% reduction in the velocity of seismic waves traveling at the base of the ultra-low velocity zone below Hawaii. According to the authors, this supports the view that the area contains much more iron than the surrounding rocks.that means it’s more intense and slower.
«It is possible that this iron-rich material is a remnant of ancient rocks of early Earth history, or even that iron is escaping from the core in an unknown way.» stated the person responsible for the project, Sanne Cottaar from Cambridge University.
The new research could also help scientists understand what’s underneath us and what drives volcanic chains like the Hawaiian Islands. In fact, one began to notice Correlation between the location of certain volcanoes, such as those in Hawaii and Iceland, and ultra-low velocity zones at the base of the mantle.
The origin of hotspot volcanoes has been widely debated, but the most accepted theory proposes that the plume-like structures pull material from the hot mantle at the core boundary reaching the surface.
With new images from the ultra-low velocity region below Hawaii, scientists also Physical evidence of what was probably the root of the pillar that fed Hawaii.
Detection of dense, iron-rich rocks will support observations made at the surface: “Basalts ejected from Hawaii have anomalous isotopic signatures that could indicate an early Earth origin or a core seepage,” Cottaar said.
Additional images of the core-mantle boundary are now needed to see if there is a dense pocket of material beneath all surface hotspots., inside the Earth. Where and how the core-mantle boundary can be found depends on where earthquakes occur and where seismometers are installed to record waves.
The team’s observations add to a growing body of evidence that suggests the Earth’s deep interior is as variable as its surface. The next step will be to apply these new techniques to improve the resolution of images of other rock areas at the core-mantle boundary and to map new areas.
Reference Work: https://www.nature.com/articles/s41467-022-30502-5
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