A Maltese scientist is among the leaders of a study that has revealed how the continental United States, Europe and Africa are drifting apart.

Matthew Agius was able to prove that the earth's tectonic plates do not just sink downward due to gravity but are also being pushed upward by material and debris due to heat activity.

This evidence of this 'upwelling' from deep beneath mid-ocean ridges are pushing the American, European and African plates further apart from each other.

Until now, conventional wisdom was that the spreading of plates is normally driven by distant gravity forces as denser parts of the plates sink back into the Earth.

Agius was the lead author of the international study published in the journal Nature. The University of Malta alumnus completed it as part of his post-doctorate at the University of Southampton, where he worked alongside other prominent scientists, Cahterine Rychert and Nicholas Harmon. 

Their discovery was the result of a 2016 experiment involving a year of data-gathering, which took place in a submerged mountain range known as the mid-Atlantic Ridge (MAR). 

“The discovery we made was an unexpected, extraordinary result. Originally, we wanted to define what makes a plate, however, the high-quality seismic data obtained allowed us to look deeper inside the Earth down to 700 km,” he told Times of Malta. 

“We discovered that at this depth there was a higher temperature than what we expected, which in turn facilitates upward movement of rocks. 

“This was unexpected because until now conventional wisdom is that upwelling beneath oceans happens at a much shallower depth within the upper 60 km below the surface,” Agius stated.

How did they do it?

One of the 39 seismometers were used to build the equivalent of an X-ray machine of the earth. Photo: Matthew Agius

He said that before this experiment, most of the knowledge on seismic activities and patterns displayed by tectonic plates came from land-based instruments.

Data from the 39 seismometers was used to build the equivalent of “an X-ray machine for the world,” allowing the researchers to use seismic waves to peer into the earth’s inner movements.

The team used the seismometers to gather data over a year, and spent ten weeks at sea to deploy and then later recover the instruments.

This was the first time so many seismometers built specifically to withstand deep-sea pressure were placed in the middle of the Atlantic ocean, providing a data-set which was essential for the team’s discovery.

“This upsurge of matter coming from beneath the MAR is literally shifting the North American continent away from the UK, about 4cm every year. The sheer size of this shifting reflects how strong the earth’s internal systems are,” Agius said.

Tectonic plates are massive chunks of material that make up the earth’s outer crust. 15 tectonic plates in total have been identified across the entire globe.

Areas such as the MAR are seismic hotspots due to the interactions between one plate and the other. When tectonic plates shift and rub against each other, seismic activity picks up. 

When a particularly strong shift occurs, natural disasters such as earthquakes and volcanic eruptions occur as a direct result. The MAR is an area in which two of these plates meet.

The upwelling movement which was proven by the team’s experiment results in shifts between the two plates. Due to heat energy coming from the earth’s magma, material rises to replace what was displaced.

What does it mean for seismology?

“Before we had this data, it was like we were trying to figure out why someone’s skin has a rash without being able to peer more closely into what’s going on inside that person’s body,” Agius said.

“Now, we have managed to accurately create a detailed image of the mantle transition zone beneath the MAR, which is essentially the border between the upper and the lower layers of the earth’s crust,” he said.

“As such, earthquakes are a secondary result of the earth’s primary internal geodynamics. These kinds of studies serve as building blocks for our holistic understanding of the origin of movements within the Earth,” the researcher added.

Agius is a University of Malta graduate with a Bachelor of Science Honours degree acquired in 2004 followed by a Master of Science degree awarded in 2007 under the supervision of Prof. Pauline Galea.