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We present measurements of 134Cs and 137Cs activity concentrations in topsoil from the greater area of the Fukushima Daiichi nuclear power plant (FDNPP) in the period 2011–2013. Fallout concentrations were determined by means of gamma-ray spectrometry, using high purity germanium (HPGe) detectors. Concentration measurements ranged up to tens of thousands Bq/kg in Fukushima and Miyagi, and less in Iwate Prefecture, indicative of the fallout distribution following the accident. Samples collected from undisturbed topsoil yielded higher fallout concentrations than those collected from ploughed/cultivated land, suggesting that soil agitation redistributed fallouts deeper in the ground. Overall, areas affected by the tsunami yielded, in general, very low topsoil concentrations. This could be attributed to tsunami debris cleanup, and to the flattening and uprooting of vegetation, which also adsorbs and absorbs fallouts, thus rendering these areas prone to soil erosion. Certain fallout hotspots identified in the inundation zone might have resulted from debris pile-up during initial cleanup. This highlights the importance of comprehensive debris cleanup. Graphical Abstract.