Two-dimensional maps of the detrended TEC from 05:50 UT to 07:25 UT on March 11, 2011. The interval of figures (a–d), (d–f), and (f–h) is 5, 10, 30 minutes, respectively. The star and cross marks represent the epicenter and the ionospheric epicenter, respectively. Gray circles represent concentric circles with the ionospheric epicenter. A movie of the detrended TEC maps with 30-second resolution is available at the NICT website (http://www.seg.nict.go.jp/2011TohokuEarthquake/).