Is there any connection between solar activity and earthquakes?

Abstract

A possible relationship between solar activity and the seismic activity of the Earth is considered. We analyzed the frequency of occurrence of earthquakes of various magnitudes with the Fourier transform: for M ≥ 7 over the period 1900—2019 and for 2.5 ≤ M ≤ 7 over the period 1973–2019. The average annual, monthly, and daily values of the solar-terrestrial variables, the number of earthquakes with intensities that fall within the specified boundaries are calculated. The epoch overlapping method was used to analyze the possible relationship between the Wolf numbers and the number of earthquakes at the corresponding moment in the cycle. 4 periods of each solar cycle were identified: the phase of ascending, maximum, descending, and minimum. Earthquakes over the entire globe and in the regions of extension and compression of the earth's crust were analyzed for each phase. No statistically significant dependencies between solar-terrestrial variables and earthquake initiation were found for all time intervals and all selected earthquake magnitudes. An interesting fact was established concerning the change in the number of earthquakes at different periods of the day. The number of earthquakes in the nighttime appreciably increases (by ~ 10 %) compared to the daytime. A slight increase in the number of earthquakes after local noon was also detected. We could not confirm the existence of a direct connection between solar activity and the seismic activity of the Earth, but we cannot also claim that such a connection does not exist.