Fukushima reactor(s) "melt-through" to "dry earth floor"

The Australian Broadcasting Corporation is reporting that one, or more, of the atomic reactors at Fukushima Daiichi which have suffered core meltdowns have actually experienced something even worse -- melt-through of multiple layers of steel (reactor pressure vessel and primary containment structure), so that molten nuclear fuel is now onto the "dry earth floor" beneath. ABC quotes senior adviser to the Japanese government Goshi Hosono (in translation): "At present there is damage to the bottom of the reactor container, we call this ‘core melting’ in English. Part of the nuclear fuel has fallen onto the dry earth floor and it's possible that it's still lodged there." The Random House Dictionary defines "China syndrome" as "a hypothetical nuclear-reactor accident in which the fuel would melt through the floor of the containment structure and burrow into the earth." If the above report is correct, the question becomes, are the desperate attempts to cool the molten nuclear fuel trying to prevent it from burrowing deeper into the ground, if it has already melted through reactor pressure vessel, primary containment, and presumably concrete foundations? Breaches of containment would create pathways for catastrophic radioactivity releases into the environment.