On January 21, 21, those radiation measures were all taken from one meter above the ground.
At the bottom right one is 6.54μSv/h (underlined red on the map)
The highest radiation measure taken is 7.48μSv/h (underlined red on the map)
Special credits to Oz Yo
These measures are not coming from government radiation monitors but from Oz Yo, a citizen himself taking measures with his own device.
Adopted model for him and his team monitoring project. https://www.facebook.com/fukuichi.mp/?hc_location=ufi