The Farallon Plate's influence on North America

Well, I was born on Avalonia, the flimsiest of plates, and right now I'm sitting on Baltica, the second oldest, with a rich history of stubbornly occupying the South Seas for the longest time, but eventually crossing the equator and now relying on the Gulf Stream to keep it warm in winter and the Scandes to keep it dry in summer, but this post is about the Farallon Plate.

The situation here is typical, in so far as there are surprisingly few earthquakes along the North American portion of the so called Ring of Fire. My time is UTC+2, by the way. I bring it up, because the Peruvian 6.5 quake shows up astonishingly clearly on this seismogram recorded in north-eastern Wyoming.

Now, the reason for this is, I think, given by this passage from the Wikipedia article on the Farallon Plate:

In April 2013 Sigloch and Mihalynuk noted that under North America these subducting slabs formed massive, essentially vertical walls of 800 km to 2,000 km deep and 400–600 km wide, forming "slab walls". One such large "slab wall" runs from north-west Canada to the eastern U.S. and extends to Central America; this "slab wall" had traditionally been associated with the subducting Farallon plate.

It would appear to me that the Farallon Plate is still subterraneously connected, with a relatively large horizontal chunk off the coast of South America, a connecting subterraneous wall, and a tiny horizontal portion off the coast of Oregon, which bends into the wall, with some smaller plate fragments being pushed into the Rockies like ice floes by the wind onto the shore. And because of that even smaller South American earthquakes show up clearly in Wyoming.

But if the wall is that deep, it effects the convection of the magma, that is, magma must either go up or down when it hits the wall, and we know that it is primarily pushing from the east into the wall going down, because only that bends the plate into a wall. Hence the North American Plate pushes westward, but since the wall absorbs the inertia of the magma, less forcefully than it otherwise would. Likewise the magmatic flow on the western side of the wall must also go down, because of friction or viscosity, or whatever you want to call it, creating negative pressure under the wall, only with less inertia, protecting North America from the kinetic energy of the Pacific Plate as well.

It would appear to me though, that at some point the wall will crack, causing a monstrous earthquake and volcanic activity. The Earth's radius is only 6371 km, 3485 km of which belong to the Earth's outer and inner core, which only leaves 2886 km in between, of which the Farallon Plate occupies up to 2000 km, defying, as it would seem, the diffusion of heat, convective cooling or not. So, if you ever wanted to make a journey to the center of the earth, better get cracking before the wall does.