These unexpected regions of the Earth's innards appear to be hotter and older than other structures nearby that are known to be sunken tectonic plates.
These ancient buried "super-continents"—known to scientists as large low-seismic-velocity provinces (LLSVPs)—were found lurking below Africa and the Pacific Ocean, entombed some 1,200 miles below the surface of the Earth.
They were discovered after geophysicists analyzed the waves of earthquakes traveling through these regions of the Earth. As ultrasound can reveal structures deep within our bodies, so can measuring subtle changes to the speed and direction of seismic waves reveals what lies deep beneath our feet.
However, the hot temperature of the LLSVPs cannot fully explain the properties of the seismic waves they were hearing emanating from these regions deep within the Earth.
The researchers suggest that the buried supercontinent regions must also be made of much larger mineral grains than the buried subducted crust, which would explain the difference in the waves they observed.
Subducting tectonic plates that end up in the slab graveyard consist of small grains because they recrystallize on their journey deep into the Earth. A small grain size means a larger number of grains and therefore also a larger number of boundaries between the grains.
he Earth's mantle is the engine that drives all these phenomena.
Take, for example, mantle plumes, which are large bubbles of hot material that rise from the Earth's deep interior as in a lava lamp. When these plumes reach the surface, they result in volcanoes forming, spewing forth lava.
Q: Is this reserved for the Time of Trouble on earth? And saying, Where is the promise of His coming? for since the fathers fell asleep, all things continue as they were from the beginning of the creation. For this they willingly are ignorant of, that by the word of God the heavens were of old, and the earth standing out of the water and in the water: Whereby the world that then was, being overflowed with water, perished: But the heavens and the earth, which are now,
Q: Is this reserved for the Time of Trouble on earth? And saying, Where is the promise of His coming? for since the fathers fell asleep, all things continue as they were from the beginning of the creation. For this they willingly are ignorant of, that by the word of God the heavens were of old, and the earth standing out of the water and in the water: Whereby the world that then was, being overflowed with water, perished: But the heavens and the earth, which are now,
by the same word are kept in store,
reserved unto fire against the day of judgment and perdition of ungodly men.
2 Peters 3:4-7