It's been over 7 months since the Fukushima I Nuclear Power Plant accident started, and it does look like natural concentration of radioactive materials may be happening in eastern Japan.
57.5 microsieverts/hour radiation from the soil in the city-owned land in Kashiwa City, Chiba sounded extraordinarily high when first reported, but maybe not so.
Fukushima Chuo Television (FCT) reported that the radiation level near the ground in a bush right by the railroad station was found to be 80 to 120 microsieverts/hour in Koriyama City, Fukushima Prefecture.
It is also possible that the radiation on that particular spot has always been high, and is being discovered only now, as more citizens are armed with personal survey meters measuring everywhere.
Koriyama City is 60 kilometers west of Fukushima I Nuclear Power Plant. Kashiwa City is 200 kilometers south, in the Tokyo Metropolitan suburb.
From FCT news (10/27/2011):
This afternoon, radiation exceeding 80 microsieverts/hour was detected from the soil near the roadside bush near the JR Koriyama station.
High school students use the road for commuting. Immediate decontamination is desirable.
This afternoon, a viewer informed FCT that a high level of radiation was confirmed on the soil near the bush located near the west entrance of JR Koriyama station.
FCT went and measured the radiation, and it was maximum 80 microsieverts/hour at 5 centimeters off the ground.
Also, when we measured the same spot with a personal survey meter of a JR personnel, it registered 120 microsieverts/hour.
The soil at this location looks to have a different color [from the soil in the area nearby], and it is considered that the high radiation is only at this location.
The location is near the bicycle parking lot, and many high school students use the road. The quick response from the authorities is desired. Koriyama City is sending the city personnel to investigate further.
If someone stays on that spot with 80 microsieverts/hr 24 hours a day for one year, the external radiation would be 700 millisieverts.
By mentioning the soil is in a different color, FCT may be indicating that someone brought the highly contaminated soil and dumped it there. It could be. But that was the suspicion for the Kashiwa City's spot, too, which proved to have been wrong.