According to the study, satellites detected a strange gravitational signal off the coast of Africa nearly 20 years ago, but new data analysis has revealed its causes. It is suggested that something unusual occurred deep within the Earth, causing a change in the planet's gravitational field, writes Focus.
Scientists have discovered an anomaly in the Earth's gravitational field that existed between 2006 and 2008. This is indicated by the analysis of data collected by the GRACE satellites, which detected a strange gravitational signal from the planet's interior during that period. The authors of the study, published in the journal Geophysical Research Letters, believe that this anomaly was caused by the movement of mass deep within the mantle of our planet, writes Live Science.
Researchers found the strange gravitational signal by analyzing data collected by the GRACE satellites. The gravitational anomaly occurred around the same time as a sharp change in the Earth's magnetic field. A significant gravitational anomaly was observed over the eastern part of the Atlantic Ocean from 2006 to 2008. It peaked in January 2007. According to the study, the gravitational anomaly was oriented from north to south and extended approximately 7,000 kilometers.
Scientists concluded that the strange anomaly, as well as the change in the Earth's magnetic field, were caused by a previously unknown geological process. The results of the study suggest that the displacement of minerals may have caused a rapid redistribution of mass in the depths of the mantle, near the core, leading to changes in the Earth's magnetic field.
The two GRACE satellites measured changes in the Earth's gravitational field from 2002 to 2017 as part of a joint mission between NASA and the German Aerospace Center. The satellites moved in sync, one after the other, around the Earth, and scientists measured the distance between the two objects to detect any changes caused by variations in the strength of the planet's gravity.
Such changes in gravity are often caused by changes in mass concentration: the greater the mass, the stronger the gravitational force. For example, water currents move mass in the ocean, which can lead to local changes in the Earth's gravitational field. In the new study, scientists analyzed GRACE data for anomalous gravitational signals that potentially arise deep within the Earth's interior, rather than from water movement on the surface.
Researchers say that the lower part of the Earth's mantle is primarily composed of magnesium silicate. The authors of the study suggest that the mass redistribution associated with the gravitational signal occurred due to a phase transition of perovskite to post-perovskite in the lower mantle, resulting in a change in the structure of magnesium silicate under pressure, leading to mass displacement in the Earth's interior.
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