of the earth's core
The Nuclear Furnace
There is some debate about the possibility that the core's center is occupied by a 5 kilometer diameter uranium furnace which augments the heat generated by the contraction of the earth and all the comets and asteroids that have delivered energy to it in the past. Because the rocky crust is a reasonable insulator we are still alive, i.e. no heat = no swirling molten iron = no magnetic field = no protection from solar radiation = hasta la vista ocean and atmosphere and ola! Mars clone.
My guess is that this is so. Heat is then continuously transmitted through the radius of the earth to vent into space via vulcanism. The entire train of vulcanism must run like this then.
Lava Lamp Bubbles as the cause of Plate Techtonics
All the motions of the crust's plates have been mapped and they show a more or less random pattern of movement. Some plates are colliding, others are separating and still others are scraping by one another ... and all combinations of the above. To me, this means that the plates are being pushed obliquely by "something". The heat transfer can't be going smoothly like light radiating from a lamp in all directions. If the lava lamp bubbles came straight up to the crust, they would not be able to push the plates sideways. Hence, the bubbles have non-perpendicular momentum relative to the crust.
There are two methods of acquiring such oblique vectors. These are by Coriolis forces operating on the bubbles as they rise through the mantle and from the moon tugging on the crust ... pulling it westbound. If this is true, there should be significantly less volcanos at the poles than near the equator (though it certainly is not impossible to have a polar volcano ... it's just unlikely that a bubble would rise straight up from the pole ... rather, most bubbles in this area would drift away from the poles as they rose and come out at lower latitudes). A notable problem with this conjecture is that the older Hawaiian Islands are to the west of Hawaii (the big island) ... meaning that Mauna Loa sits on the current "hot spot" which is drifting east under the crust. Well, this is a problem because I would expect the opposite to be the case if the east-west differential between the crust and mantle were caused by an oblique hit from underneath, i.e. the hot spot should be drifting in the other direction.
Angular Momentum Conservation
Observe that nature tends not to do things smoothly but rather chaotically which flattens out to smooth over long time periods. For instance, a flag in a constant breeze develops ripples which are more or less identical from one time period to the other. The air can't pass over the flag without turbulence which turns into a fairly orderly pattern of waves in the flag fabric. The same is undoubtedly true of convection in the core and mantle. We get chaotic bubbles which are orderly over long time periods.
As heat is taken from the core, the core alternately heats and cools in the aforementioned chaotic manner. The core is in a cooling phase right now. Thus, the core has shrunk somewhat because it has cooled. Hence, it speeds up to conserve angular momentum. On the other hand, the mantle is in its heating phase and has expanded. Hence, it slows down a little. The situation should change over time and the core-mantle interface should flip relative directions.
The Effect of the Moon
The moon's gravitational tug on all of this muddies the theoretical waters. How much does it pull on the crust? Is it enough to override the oblique push in the opposite direction in the case of Hawaii? Or does it pull everything uniformly so that we can "x" it out of the problem?
I don't know.
But we now have another way for everybody to die to add to mega-tsunamis, super-volcanos, asteroid collisions, close proximity novas, black holes, magnetic pole flipping, global warming, global cooling, pandemic bird flu-ebola, penicillin-resistant bacteria, atomic terrorist attacks ... hey, I'm keepin' track of all these things.