It may well be fundamental to mainstream geological thinking but to the man in the street it doesn’t mean very much is actualy different. Basically, it is all guesswork about how deep those pieces of plate are subducted at plate margins. For most of earth history they only subducted halfway down into the Mantle – until the fundamental change. It is claimed they now reach down as far as the margins of the outer core. See https://phys.org/news/2023-07-proof-earth-plate-tectonics-underwent.html … and was sent in by Gary. He may have been thinking of recent – as in human perception – but this is geological recent [which is a long time ago].
Earth, we are told, is unique, in that it has plate tectonics. This has not been observed on any other planets – and some geologists prefer an expanding earth model. They would need to find evidence of expanding planets in order to give the theory a bit of meat to the bone. We might rephrase that statement – earth is unique because geological academics have proposed the idea plate tectonics plays a role in volcanoes and earthquakes.
Plate tectonics is the movement and interaction of tectonic plates on the surface of the earth, an idea created to dilute Wegener’s theory of continental drift. Plate tectonics, conveniently, is extremely slow. So slow one cannot detect it. The link describes it as a very slow creeping motion of the earth’s Mantle, which they call convection. This is the process that carries heat from the interior to the planet’s surface, an idea that illustrates how little is known about the origin of earthquakes. They even call the Mantle a plate graveyard. When plates collide one of them sinks into the Mantle – which avoids the idea of expansion of the earth. Neat trick and illustrates how keen they were to bury the expanding earth theory in their plate graveyard.
In the new study published in the journal Nature we have more or less what was siad in the first couple of sentences. However, the process whereby they arrived at their conclusion is interesting.