The Analytical Contribution to the Theory of Solar-induced Earthquakes: the Croatian December 2020 M=6.4 Case Study

Solar-induced earthquakes are a relatively new field of research of possible connection between events originating from Sun, and the Earth's lithosphere dynamics. This is a theory that tries to explain the temporal correlation between the solar activity increase, particularly measured using proton density values, and occurrence of the strongest earthquakes on Earth. In this paper, the case study of Croatian major earthquake in December 2020 was investigated. The increase in proton density as measured by STEREO satellite, by +4.2 standard deviations from the monthly mean value, preceded the main shock of M=6.4 by 16 hours. Such proton density increases, within one day before major earthquake, agrees with previous research where strong temporal correlation of those two events was found.