Geophysicists from the University of Maryland studied data from thousands of recorded seismic waves and sound waves traveling through our planet, to search for echoes from the boundary between Earth’s molten core and the solid mantle layer above it.
The echoes led to the discovery of additional widespread, heterogenous structures, mainly areas of suspiciously dense, hot rock in places previously unmapped.
Researchers are not sure about the chemical composition of the structures, and past analysis has only revealed a few limited details about them.
An advanced understanding of their shape might reveal the geologic processes that happen deep under our planet’s surface. Such a discovery could provide crucial information about Earth’s tectonics and evolution.
The new research provides the first advanced view of the core-mantle boundary over an extended area in excellent resolution.
The research was published in the journal Science on June 12, 2020.
The scientists analyzed echoes of seismic waves traveling beneath the Pacific Ocean basin. Their work unveiled a previously unknown structure beneath the volcanic Marquesas Islands in the South Pacific. It proved that the structure found beneath the Hawaiian Islands is considerably more massive than previously thought.
Doyeon Kim, a postdoctoral fellow from the UMD Department of Geology and primary author of the study, said: “By looking at thousands of core-mantle boundary echoes at once, instead of focusing on a few at a time, as is usually done, we have gotten a totally new perspective,”
“This is showing us that the core-mantle boundary region has lots of structures that can produce these echoes, and that was something we didn’t realize before because we only had a narrow view,” he added.
Earthquakes produce seismic waves underneath the Earth’s surface that are capable of traveling thousands of miles. When they encounter changes in rock density, composition, or temperature, their speed changes, or, they scatter, thus resulting in detectable echoes.