ULF magnetic field depression as a possible precursor to the 2011/3.11 Japan earthquake

• Дата: 2013
• Автори: Schekotov, A., Fedorov, E., Hobara, Y., Hayakawa, M.
• Формат: Стаття
• Мова: English
• Опубліковано: Інститут радіофізики і електроніки ім. А.Я. Усикова НАН України 2013
• Назва видання: Радіофізика та електроніка
• Теми: Распространение радиоволн, радиолокация и дистанционное зондирование
• Онлайн доступ: http://dspace.nbuv.gov.ua/handle/123456789/105962
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: ULF magnetic field depression as a possible precursor to the 2011/3.11 Japan earthquake / A. Schekotov, E. Fedorov, Y. Hobara, M. Hayakawa // Радіофізика та електроніка. — 2013. — Т. 4(18), № 1. — С. 47-52. — Бібліогр.: 21 назв. — англ.

The depression (reduction in amplitude) of ULF magnetic field variations of magnetospheric origin is studied at various distances from the epicenter of the strongest earthquake (EQ), which occurred in Japan on March 11, 2011. For this purpose, we have used the ULF data in Japan recorded by fluxgate magnetometers at three places located at distances of ~300 km to ~1300 km from the epicenter of the main shock. The period of data analysis is from December 1, 2010 to May 31, 2011. We have found a sharp depression of the horizontal ULF magnetic field component at the frequency of 0.03…0.05 Hz (30…50 mHz) at all of three Japanese observatories (Kakioka, Memambetsu and Kanoya) three days before the first strong foreshock (Mw 7.5) and five days before the main shock (Mw 9). This maximum depression is found to be several times greater than all previous deviations, but the depression seems to be most enhanced at Kakioka, the station nearest to the EQ epicenter. So that it is likely that this phenomenon could be a possible precursor to the huge 3.11 EQ.