Rock is laid down in layers. Think of it like the layers in a cake. Each layer of rock, no matter its geologic type, will be made up of minerals. These minerals have a simpliar composition for each layer. In a fault line, the layer shear or shift in relation to one another. This shift can then cause one layer of a certain mineral to come into contact with a different layer. The connection of dissimilar minerals can generate a current when moist or wet. This current - a weak electric current, will also generate a magnetic field that can cause similar effect as underground water. The solution is to move your sleeping location or mitigate the fault line.
Source: https://en.wikipedia.org/wiki/Fault_(geology)