According to a recent research conducted by a scientist at the University of Chicago, it is possible that a layer of exceptionally malleable rock encircles the Earth, located at the bottommost part of the upper mantle.
Deep earthquakes could reveal secrets of the Earth's mantle | University of Chicago News
According to the study, the Earth's mantle is made up of layers of solid rock that extend from the bottom of the crust to the top of the core. However, Jacobsen and his team found evidence that there may be a layer of "ultra-low velocity zone" (ULVZ) at the very bottom of the mantle, just above the core.
This ULVZ layer is characterized by a slowing down of seismic waves as they pass through it, suggesting that the rock in this layer is more fluid or molten than the surrounding solid rock. The researchers used data from earthquake waves that traveled through the Earth to create a three-dimensional map of the mantle, which revealed the presence of the ULVZ layer.
The study suggests that the ULVZ layer may be responsible for some of the unusual features of the Earth's magnetic field, and that it may play a role in the movement of tectonic plates. However, more research is needed to fully understand the properties and behavior of this layer of fluid rock.
Overall, the study provides new insights into the structure and dynamics of the Earth's mantle, and highlights the ongoing scientific quest to understand our planet's deep interior.
In recent years, scientists have been using increasingly sophisticated techniques to study the mantle in more detail. One such technique is seismology, which involves using seismic waves generated by earthquakes to map the structure of the Earth's interior. By analyzing the behavior of these waves as they travel through the mantle, scientists can infer information about the physical properties of the rock.
In the study published in Science in 2019, geophysicist Steve Jacobsen and his team at the University of Chicago used seismology data to create a three-dimensional map of the Earth's mantle. They focused on a region called the "D" layer, which lies just above the core-mantle boundary at a depth of about 2,700 kilometers (1,700 miles).
What they found was surprising: a layer of rock in the D layer that exhibited a significant slowing down of seismic waves as they passed through it. This suggested that the rock in this region was more fluid or molten than the surrounding solid rock, and that it was capable of transmitting seismic waves much more slowly.
This layer of fluid rock is now known as the "ultra-low velocity zone" (ULVZ), and it is estimated to be about 100 kilometers (62 miles) thick. According to Jacobsen and his team, the ULVZ could represent a major boundary within the Earth's mantle, marking the transition from solid to partially molten rock.
One of the most intriguing aspects of the ULVZ is its potential connection to the Earth's magnetic field. The magnetic field is generated by the motion of molten iron in the outer core, but it is influenced by the structure and composition of the mantle above. Jacobsen and his team suggest that the ULVZ could be responsible for some of the unusual features of the magnetic field, such as its so-called "South Atlantic Anomaly," where the field is weaker than in other regions.
In addition, the ULVZ could play a role in the movement of tectonic plates, which are the large, floating slabs of rock that make up the Earth's crust. The movement of these plates is driven by convection in the mantle, which is in turn affected by the properties of the rock. Understanding the ULVZ could therefore help us to better understand how tectonic plates move and interact with each other.
Despite these potential connections, the ULVZ remains a relatively mysterious region of the Earth's mantle. Further research will be needed to determine the exact composition and behavior of the fluid rock in this layer, as well as its precise role in the planet's geology and dynamics. Nonetheless, the discovery of the ULVZ represents an important step forward in our understanding of the Earth's deep interior, and underscores the ongoing scientific quest to unlock the secrets of our planet's past and future.
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