[M-IS04] Interdisciplinary studies on pre-earthquake processes

[MIS04-P11] Impacts of geomagnetic storms on seismicity: A case study for 2013 and 2015 St. Patrick's Day geomagnetic storms

*Dimitar Ouzounov¹、Galina Khachikyan² (1.Institute for Earth, Computing, Human and Observing (Institute for ECHO), Chapman University, Orange, California, USA、2.Institute of Seismology, Almaty, Kazakhstan)

キーワード：geomagnetic storms , earthquake, space weather

We present the results of a response of global seismicity to St. Patrick's Day (March 17) storms in 2013 and 2015, which occurred during rather similar solar flux levels and nearly identical storm sudden commencement times. A similar pattern of most actual earthquake occurrences after storms is revealed. Namely, with a time delay of ~30 and ~39 days after storm onsets in 2013 and 2015, respectively, the strong crust earthquakes occurred at continental areas in Iran (M7.7, April 16, 2013) and Nepal (M7.8, April 25, 2015). Then, with a time delay of ~68 and ~74 days after storm onsets in 2013 and 2015, respectively, the solid deep-focused earthquakes occurred beneath the Sea of Okhotsk (M8.3, May 24, 2013, Russia) and beneath the Pacific Ocean (M7.8, May 30, 2015, Japan). It is shown that in the time of geomagnetic storm onsets (06:04 UT in 2013 and 04:48 UT in 2015), the longitudes at which the future strong earthquakes occurred were located under the polar cusps where the solar wind plasma would have direct access to the Earth's environment. The results support our earlier findings (Ouzounov and Khachikyan, 2022) that: 1/ that seismic activity may respond to geomagnetic storm onset with a time delay of up to ~two months, and 2/ the geomagnetic poles and the earthquake epicenters in East Asia are centered around longitudes of the location of geomagnetic poles in the Northern and Southern Hemisphere.