Toads. Clouds. Radon gas. Scientists have studied the movement of each of these in desperate attempts to improve earthquake detection methods by even just a few minutes. Now there’s a technology to test the radon theory for good and possibly give warning days before a quake.
As uranium in the earth decays, it emits radon gas, some of which collects in pockets underground. Some seismologists hypothesize that earth shifts imperceptibly in the days before a quake, causing fractures that puncture the pockets and release more radon. But it would take a lot of data to test the theory.