The Earths global seismic activity is analyzed to identify a possible impact of strong magnetic storms. We chose as the primary quantitative measure of the Earths global seismic activity the total number of strong (magnitude M ≥ 5.0) crustal (hypocentral depth 0 ≤ h ≤ 60 km) earthquakes per day over the world (). The geomagnetic activity and the strength of each particular magnetic storm were estimated based on the hourly values of the -index. Only strong geomagnetic storms that meet the condition ≤ −150 nT were considered. The storm database under investigation includes only those events for which the final hourly values for the period from 1957 to 2016 are available. The modified superposed epoch method was used as the main analysis tool. The reference (zero) day was the day on which the minimum DST-value was recorded. It was found that on the day preceding the reference day (day minus 1), the Earths global seismic activity decreases significantly as concerns the sudden commencement magnetic storms (). On day zero, the situation is not as clear, but a certain increase in the Earths global seismic activity is observed for the gradual commencement magnetic storms (). Moreover, on day +7, the Earths seismic activity for such storms increases significantly. Possible physical mechanisms are proposed and discussed to explain this behavior of the global seismic activity of the Earth on the basis of extremely simplified quantitative estimates.
V.V. Hegai (Wed,) studied this question.