ИСТИНА

The work is devoted to the study of the relationship between variations in the interplanetary magnetic field (IMF) and seismic activity. The sign of the IMF radial component is used as a control parameter on which the oscillation mode of the Earth's magnetosphere depends. The sign reversal signals the probable crossing of the boundary between the IMF sectors by the Earth, or, in other words, the crossing of the heliospheric current sheet by the Earth. The hypothesis is that IMF fluctuations, penetrating into the magnetosphere from the foreshock region, excite ULF electromagnetic oscillations in the magnetosphere, which, in principle, can affect the physical processes in upcoming earthquake sources. Information about the IMF sector structure was extracted from the IZMIRAN catalog (http://www.izmiran.ru). To obtain information on seismicity, we used the following catalogs: global Catalog of earthquakes of the International Seismological Center ISC, 1964–2010 (http://www.isc.ac.uk), global Catalog of the National Information Center of the US Geological Survey USGS/NEIC, 1973–2014 (https://www.usgs.gov), regional Northern California Earthquake Catalog, 1968-2007 (http://www.ncedc.org), regional Southern California Earthquake Catalog, 1983-2008 (http://www.data.scec.org) and regional Greece Earthquake Catalog, 1964- 2009 (http://www.gein.noa.gr). A weak but statistically significant relationship between variations in the interplanetary magnetic field (IMF) and seismic activity has been found. When the Earth crosses the current sheet of the heliosphere, an increase in both global and regional seismic activity is observed. The work was supported by the project of the RFBR 18-05-00096 and the state assignment program of the IPhE RAS.