This video is incredible!!!
At 2:35 It allows to see plate tectonic in action in (near) real time, just look at the motion of the lava lake speeded up; a thin cooler crust, separated in several pieces delimited by "lines of fire" floats on the lava below and gets dragged to the other side of the lake, where it sinks
Reminds me of some animation I have seen about the plate tectonic where it was simulated the movemento fo plates around the faults.
Great Video from BBC series, THE POWER OF THE EARTH, go and get it!
Hosted by Ian Stewart