%0 Journal Article %A Hayakawa, Masashi %A Hobara, Y. %A Rozhnoi, A. %A Solovieva, M. %A Ohta, K. %A Izutsu, J. %A Nakamura, T. %A Yasuda, Y. %A Yamaguchi, H. %A Kasahara, Y. %D 2012 %I Begell House %K ionospheric precursor, VLF/LF propagation, 2011/03/11 Japan EQ %N 18 %P 1687-1706 %R 10.1615/TelecomRadEng.v71.i18.60 %T THE IONOSPHERIC PRECURSOR TO THE 2011 MARCH 11 EARTHQUAKE AS BASED ON THE JAPAN-PACIFIC SUBIONOSPHERIC VLF/LF NETWORK OBSERVATION %U https://www.dl.begellhouse.com/journals/0632a9d54950b268,48d4e5ab0b169f59,5a12a8431731e02a.html %V 71 %X By using the network observations of sub-ionospheric VLF/LF signals in Japan and Russia, we found a significant ionospheric perturbation prior to the 2011/3/11 Japan earthquake (EQ). A remarkable decrease was detected in the nighttime amplitude and increase in the dispersion on March 5 and 6, on the paths from NLK (Seattle, USA) to Chofu, Kochi and Kasugai. We found also the anomalies in March 1-6 period and minima in the nighttime amplitude on March 3 and 4 on the path JJI (Miyazaki, Kyushu) - Kamchatka, Russia. We describe perturbations and discuss the relevant geophysical environment. Data are compared with perturbations of many inland EQs, and with the spatial scale of similar oceanic Sumatra EQ in 2004. The generation mechanism of ionospheric perturbations is outlined. %8 2012-12-12