I have absolutely no insider information as far as JAL matters are concerned , but it may be interesting to see what ACMS type data shows up in the preceding weeks regarding EGT's , FF and N1/N2 figures for that particular engine.
Crack propagation in the combustion liners have in the past caused the FADEC to schedule more fuel in order to achieve the same N1 as the healthy engine.
It gets to the stage when the combustion liner lets go completely and ends up taking a few turbine blades with it as it all exits out of the jet-pipe , along with a bl**dy great flame.
This of course conjecture , but also a possible and quite likely cause.