Aging satellite reveals Earth’s inner structure

The European Space Agency’s GOCE mission ended more than seven years ago, but scientists are still discovering substantial discoveries from gravity data from the retired satellite – allowing us to dive deep into the interior of the Earth and learn what makes him tick.

Scientists have combined GOCE data with surface measurements to create a new model of the earth’s crust and upper mantle, recent study finds published in the International Geophysical Journal.

This is the first time that a model of the Earth’s interior has been created in this way – and it unearths (pun intended) new plate tectonic processes – a feature of our planet that causes volcanic eruptions. and earthquakes.

Space gravity data improves our picture of the Earth’s inner structure

Crucial to the science of plate tectonics is a solid understanding of the Earth’s lithosphere – which is made up of the planet’s outer rocky crust, in addition to the molten, semi-molten upper layers of the planet’s upper mantle.

Plate tectonics describes how the earth’s crust is divided into a patchwork of plates sliding in slow, monumental motion over the moving top of the upper mantle. When this happens, it forms a new seabed along mid-ocean ridges, volcanoes become critical and erupt, mountains rise, and earthquakes occur. Improving our scientific understanding of these processes depends on advancing knowledge about differences in the chemical composition of the lithosphere and variations in temperature.

Classically, geophysicists measure the speed of propagation of seismic waves once an earthquake begins to predict and study the distribution of physical properties beneath the Earth’s surface. The speed of movement of seismic waves across the planet is primarily determined by the temperature of the rocks underground – and density, but less.

Gravity data from space dramatically improves this picture – because the effect of gravity is directly related to the density of different parts of the Earth. Data from orbiting satellites can provide uniform accuracy and coverage across the planet, especially where ground measurements rarely, if ever, occur.

Earth’s lithosphere is different under different oceans

The new research shows how scientists built a new model of the lithosphere by combining seismological data collected via petrological data and seismological observations (on foot). The first comes from the study of rocks that have been brought to the planet’s surface – in addition to laboratories where the extreme pressures and instantaneous death temperatures of the Earth’s interior are recreated for scientific research.

“Earlier global models of the crust or lithosphere suffered from limited resolution or were based on a single method or data set,” said paper co-author Javier Fullea, also of the Complutense University of Madrid and the Institute of Advanced Studies, according to a report of “Only recently available models were able to combine multiple geophysical data, but they were often only at regional scales or were limited by how the different data are integrated.”

“For the first time, we were able to create a new model that combines multiple global-scale terrestrial and GOCE satellite data sets in a joint inversion that describes the actual temperature and rock composition of the mantle,” Fullea added.

GOCE’s new model showed for the first time just how different the sub-lithospheric mantle is under different oceans – while also revealing more about the speed of propagation of mid-ocean ridges, suggesting that their speed and morphology may be related to the deep thermal and chemical structure. . With this knowledge, we may one day make more accurate long-term predictions about seismic activity as our living world evolves.

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