Earth’s tectonic plates are moving faster now than at any point in the last 2 billion years, according to the latest study of plate movements.
But the result is controversial, since previous work seemed to show the opposite.
If this is true, it means that Silfra, this Iceland spot where you can dive between the European and American tectonic plates will soon become a highway! And could it explain the increasing number of volcanic eruptions worldwide?
A geochemist at the New Mexico Institute of Mining and Technology in Socorro and his colleagues looked at how often new mountain belts form when tectonic plates collide with one another. They then combined these measurements with magnetic data from volcanic rocks to work out at which latitude the rocks formed and how quickly the continents had moved. Both techniques showed plate motion has accelerated. The average rate of continental collisions, and the average speed with which the continents change latitude, has doubled over the last 2 billion years.
If true, the result could be explained by another surprising recent discovery: the presence of more water within Earth’s mantle than in all of the oceans combined. Indeed, when crust sinks back into the mantle, oceanic water gets sucked down too, and although most comes back to the surface in volcanic emissions, over the aeons the store of water in the mantle has grown vast. Some of this water forms hydrous minerals that essentially make the mantle more runny, speeding up the flow of rock. The effect is strong enough to overcome the stiffening of the mantle caused by the gradual cooling inside Earth, he says.
These increasing tectonic activity are controversial since a study last year concluded that plate motion has been slowing for 1.2 billion years.
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