Raxu obviously didn't know that the terrain would act to his disadvantage. But it was rather common sense that existence of an open hot spring and the rocky texture in the surrounding hinted that the land was close to groundwater.
The open hot spring has relaxing body temperature, but the closed groundwater didn't. Its temperature was volcanic, and the terrifying heatwaves crashed on the circular barrier surrounding Raxu.
Almost everyone was aware the most of the heat in hot streams were created by the decay of naturally radioactive elements.
Elements which existed in the Earth's mantle...
Ever since the era of evolution started, Earth's core has already undergone a mutation, and the nature of radioactive elements has transmuted.
In the open spring, the heat from these elements carried strong therapeutic properties, but in the closed groundwater that Raxu has fallen, the same elements played a role of toxic.
