Fig. 4From: Modifications of the ionosphere prior to large earthquakes: report from the Ionosphere Precursor Study GroupNmF2 at Khabarovsk from February 9 to April 9, 2011. Black line indicates monthly average NmF2 centered on each day, and blue line indicates the daily NmF2. Vertical lines indicate the days of EQs. The largest night-time increase of NmF2 is marked by a black arrow Back to article page