ALBERT

Description: Strong natural hazards events are assumed to be significant sites to investigate the lithosphere-atmosphere-ionosphere coupling (LAIC), showing possibly a multitude of processes up to high altitudes. Until now there is no clear consensus on how specific mechanisms affect the different layers and important questions persist. In this study we analyse European earthquake events with magnitudes M ≥ 5 based on the USGS catalogue, a second focal point is a particular class of volcanic eruptions selected from Mt. Etna (Sicily, Italy) activity periods. We examine electric field variations in the earth-ionosphere waveguide along radio paths between narrowband VLF/LF transmitters and ground-based receiver facilities (INFREP network). Those observations are combined with in-situ satellite magnetic field measurements from the missions Swarm and CSES-1 at LEO altitudes. For both investigations spatio-temporal proximity to the event sites is necessary. The selected bundling of the two field parameters enables the steady VLF/LF electric-field measurements from the lithosphere up to the ionospheric D/E-region and the satellite measurements assess parts at the end of the propagation channel in the ionospheric F-region at about 500 km altitude.Results for volcanic eruptions show a decrease in the VLF/LF electric fields of up to 10 dB with fluctuations in the frequency range of atmospheric gravity waves (AGWs). Earthquakes exhibit larger VLF/LF amplitude values after the event (night-time amplitude method). We find no clear signatures in the ionospheric satellite magnetic field measurements, but future missions like CSES-2 double the revisiting frequency above natural hazards prone areas and will facilitate further in-detail investigations.