Scientists have confirmed the existence of earthquakes in the Earth's mantle
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- Scientists have confirmed the existence of earthquakes in the Earth's mantle
American seismologists have confirmed the existence of a rare class of seismic events — earthquakes in the Earth's upper mantle, occurring at depths from 68 to 90 km below the surface. The discovery refutes previous ideas about where exactly seismic tremors can occur under the continents. This was reported on June 3 in the journal Science Daily.
"This is an example of an earthquake that originates in extremely unusual conditions — at high temperature and high pressure. Almost all the matter at this depth will flow, it looks like butterscotch, and on a scale of millions of years," Keith Cooper, a professor of geology, described the phenomenon.
The starting point of the study was the tremor on February 24, 1979 near the village of Randolph in Utah — magnitude 3.8, unnoticed by residents on the surface. George Zant, a postdoctoral fellow at the University of Utah, then calculated the depth of the hearth at about 90 km below sea level, that is, well below the lower boundary of the earth's crust. He failed to convince his colleagues of the reality of the anomaly.
Decades later, Cooper and his team reanalyzed the wave data from this and eight other suspected deep earthquakes in Northern Utah and Southwestern Wyoming and confirmed that the foci of all nine events are located in the upper mantle.
The hypothesis was further supported by the earthquake of September 10, 2025 in the Uintah basin in Utah: magnitude 4.1, the depth of the source is about 68 km, that is, more than 20 km below the surface of the Mohorovichich, delimiting the crust and mantle.
Scientists associate such events with the edge of the Wyoming Craton, an ancient stable block of the lithosphere around which the mantle flow. This interaction creates increased stresses in the rocks. The peculiarity of such tremors is the complete absence of foreshocks and aftershocks typical of shallow earthquakes.
On April 23, Science Daily reported the discovery of traces of tectonic plates in the Earth's mantle. The researchers have compiled a global map of deformations in the lower mantle and found that most of them are confined to the submergence zones of ancient tectonic plates.
Переведено сервисом «Яндекс Переводчик»
