The molten core of several Fukushima Daiichi reactors is sinking through the Earth’s crust and appears to be in early stages of a “China Syndrome,” according to Uehara Haruo, architect of Fukushima Daiichi’s Reactor No. 3 and former president of Saga University, Fukushima Diary reports.

If fuel has reached an underground water vein, it will cause contamination of underground water, soil, and sea, he said. “Moreover, if the underground water vein keeps being heated for long time, a massive hydrovolcanic explosion will be caused.”