Correlations between solid tides and worldwide earthquakes M_S ≥ 7.0 since 1900

Abstract. Most studies on the correlations between earthquakes and solid tides mainly concluded the syzygies (i.e. new or full moons) of each lunar cycle have more earthquakes than other days in the month. We show a correlation between the aftershock sequence of the M_L = 6.3 Christchurch, New Zealand, earthquake and the diurnal solid tide. M_s ≥ 7 earthquakes worldwide since 1900 are more likely to occur during the 0°, 90°, 180° or 270° phases (i.e. earthquake-prone phases) of the semidiurnal solid earth tidal curve (M₂). Thus, the semidiurnal solid tides triggers earthquakes. However, the long-term triggering effect of the lunar periodicity is uncertain. This proposal is helpful in defining possible origin times of aftershocks several days after a mainshock and can be used for warning of subsequent larger shocks.