A rift in the tectonic plates had this impact on land in the Myvatn District in Iceland. Photo: 123RF
One of the big mysteries surrounding tectonic plate movement may have been uncovered in new research.
Researchers from Victoria University of Wellington and GNS Science have identified a 10km-thick layer containing some softer, melted rock at the bottom of the Pacific plate and the Earth's underlying mantle.
Professor Martha Savage from Victoria University said while scientists knew that relative movement between the Earth's plates was the cause of earthquakes, volcanoes, and tsunamis, "one of the unanswered questions in plate tectonics is how these massive plates move with respect to one another".
The softer melted rock layer effectively lowers friction and acts like a skid, aiding plate movement.
A graphic showing volcanic activity and Earth's tectonic plates. Photo: Encyclopaedia Britannica/UIG Via Getty Images
Principle scientist at GNS Stuart Henrys said the layer the plates move on was comparable to jam in a cake.
From the way the plates moved through 'the jam', they were able to distinguish some physical properties and layering of the substance, he said.
Professor Savage said the discovery will help scientists understand the processes shaping the planet.
"The bases of tectonic plates are the biggest 'faults' we have within the Earth in terms of their length and amount of movement.
"Therefore, what we learn from these deep and well-worn faults may have relevance to fault events in the crust closer to the Earth's surface," she said.
At a thickness of approximately 100km, the Pacific plate is the largest of the plates that cover the globe.
It would be interesting to see if what they found on the Pacific plate was universal, Henry said.
He said it would also be interesting to know if the same sort of tectonic force behaved in the same way on other planets.
