Héctor Sacristán 

In this article, I show lines of evidence supporting a modulation of volcanic activity and some weather phenomena by solar wind conditions in the near-Earth environment. On a daily timescale, a correlation is found between the LP earthquake activity of Kilauea volcano, related to magma transport, and the Bx component of the interplanetary magnetic field as measured in the OMNI database for specific intervals in 1995 and 2003. On yearly timescales, during the 2000-2018 period, I show a correlation between the inflation rates of four intraplate volcanoes (Kilauea, Mauna Loa, Sierra Negra, and Yellowstone) and solar wind conditions where the volcanoes' activity seemed positively correlated with solar wind dynamic pressure. Additional volcanoes also showed similar behavior to the four mentioned, in that they experienced a surge in activity in 2004-2007. I compile a list of ≥400 g hail events in Spain since 1850, from newspapers, which are given in the appendix, and is used to study the variation in the frequency of large hail events, finding a similar pattern to that seen in volcanic activity. The hail events are seen to concentrate towards the middle of the 11-year solar cycles when the interplanetary magnetic field tends to be at its strongest. Additional yearly/decadal correlations between different types of volcanic activity, Spanish hail events, and North Atlantic accumulated cyclone energy, reveal complex patterns that appear to be independent of solar activity, but show a relation between volcanism and weather processes. A possible 50-year oscillation across all three is identified. In the last section, I discuss possible mechanisms governing the observed patterns and I propose that the deformation of Earth’s magnetosphere by solar wind, combined with the planet’s rotation, exposes locations in the planet to a changing magnetic field which causes electromagnetic induction in ionic conductors like seawater and magma, with ensuing currents dispersing heat or having other effects, thereby influencing related processes in the atmosphere and geosphere. The possible influence of induced electric currents in magma chemistry is also discussed, after having briefly reviewed different magma compositions. I also propose 50-year oscillations to be internally driven, given there may be factors on Earth that influence the process of electromagnetic induction, but I do not try to describe any specific mechanism.