Prior to an earthquake:
1) P-wave velocity decreases in stage 2 before returning to normal just before the quake (P-wave changes before major earthquakes)
2) tilts & bulges increase in stage 2, stay there in stage 3, then decrease quickly to normal after the quake
3) local earthquakes increases to stage 2 then decreases during, before increasing up to a quake, then sharply down to normal after - foreshocks
4) radon gas emissions increases in stage 2, stays steady in stage 3, then back to normal after quake
5) groundwater level decreases from stage 2, until end of stage 2, before rising back to normal before the quake
6) electrical resistivity, gradually decreases after stage 1, until the quake, then rises to normal after the quake