Fig. 3From: Modifications of the ionosphere prior to large earthquakes: report from the Ionosphere Precursor Study GroupVariation of NmF2 expressed by NmF2/NmF2 mean for 11 ionosonde stations located nearly at the same longitude of Japan. Red and black colors indicate the increase and decrease respectively. Blue thin vertical line indicates the time of EQ occurrence. Note the similar variation at Wakkanai, Beijin, I-Cheon, Kokubunji, and Jeju, NmF2/NmF2 mean at Yamagawa does not show any similarity to the four stations. NmF2/NmF2 mean at Yakutsuku, Brisbane, Perth, and Canberra shows the negative value. These facts seem to suggest the ionopshere disturbancce related to EQBack to article page