Right now I am having some dialog with people about this very deep moderate earthquake east of the Tonga Subduction Trench. A scientist shared this link to this earthquake after I mentioned deeply seated and rotating subducted plates, and their related earthquakes. The question right now is: Is this little earthquake due to the movement of a subducted plate, deep within the mantle? Why does this question pop up? Will look at how deep this earthquake is! It's way down in the earth's mantle, at 347 kilometers (216 miles) deep! To the west of the the earthquake is the Tonga Trench, a very deep trench at a place where an thin and heavy oceanic plate is diving under another plate. This is a very active subduction zone, one that kicks off 7 magnitude plus earthquakes on a regular basis!
Note: A typical earthquake is at a depth from 25 miles down to 2 miles down.
This event is unique. I recently attended an earthquake conference and listened to a presentation about the possibilities of moving and rotating sinking plates, those deeply seated in the mantle. The mantle is a thick layer of highly pressurized semi-fluid foam-like hot rock and other materials. It is a zone between our thin crust and the molten metallic core system. At least, this is the commonly accepted model within the science community.
I'm going to search around for some papers written by some scientists I know, if these papers are available. If I find them, I will share them and blog about what I think.
Magnitude 4.8 - TONGA