摘要：The objective of this contribution is to get new insights into the efects of magnetic feld variations of natural and anthropogenic origin on broad-band seismic stations.Regarding natural sources of magnetic perturbations, we have investigated if the Sudden Storm Commencements (SSC) cataloged during the 24th solar cycle (2008–2019) can be systematically identifed in broad-band seismic stations distributed worldwide.The results show that the 23 SSC events with a mean amplitude above 30 nT and most of those with lower energy but still clearly identifed in the magnetometer detection network can be observed at broad-band stations’ network using a simple low-pass flter. Although the preliminary impulse of those signals is usually stronger at stations located at high latitudes, major SSC are observed at seismic stations distributed worldwide.Regarding anthropogenic sources, we focus on the short period seismic signals recorded in urban environments which are correlated with the activity of the railway transportation system.We have analyzed collocated measurements of electric feld and seismic signals within Barcelona, evidencing that signifcant changes in the electric feld following the activity of the transportation systems can be attributed to leakage currents transmitted to the soil by trains.During space weather events, electric currents in the magnetosphere and ionosphere experience large variations inducing telluric currents near the Earth surface, which in turn generate a secondary magnetic feld.In the case of underground trains, leakage currents are transmitted to the soil, which in turn can result in local variations in the magnetic feld.The observed signals in modern seismometers can be related to the reaction of the suspension springs to these magnetic feld variations or to the efect of the magnetic feld variations on the force transducers used to keep the mass fxed.
关键词：Sudden Storm Commencements; Anthropogenic sources of magnetic noise; Seismic instrumentation
