Fig. 3

Magnetic amplitude of the SSC events vs. seismic observations. a Mean amplitude of the significant SSC events during the 24th solar cycle (red bars) compared with the number of observations of each event in the broad-band stations (black bars). b Total magnetic intensity (NCEI Geomagnetic Modeling Team and British Geological Survey 2019) for year 2018 compared to the number of SSC observations for each investigated broad-band seismic station. F isolines are shown every 1000 nT below 35,000 nT and every 5000 nT above this value to better constrain the SAA anomaly. The size and gray saturation of the circles represent the number of observations at each seismic site, with small white dots representing seismic sites without observations