The role of solar heat in earthquake activity

We have shown, in a previous work, that the solar activity causally influences earthquake activity on Earth [M. H. Junqueira Saldanha and Y. Hirata, Chaos 32, 061107 (2022)]. However, the mechanisms by which the Sun can affect seismic activity on Earth are still unknown. Here, we examine the hypothesis that one of such influences is through heat. To support this, we present a diverse array of evidence, including the existence of variation in Earth’s seismicity throughout the different seasons; the presence of shared dynamical information and a large degree of non-determinism in solar activity and earthquakes; an increase in earthquake predictability if surface atmospheric temperature is considered an independent variable; and a variation in such predictability when accounting for a delayed sunspot time series, which aligns with the expected timescales of heat transfer and its effects on Earth’s systems.