Concerned with the lack of understandable information in the current situation, the Institute for Information Design Japan is collecting all available measurements to compile a consistent and comprehensive Japan Radiation Map. Most of the data used are updated hourly, however some sources provide data in larger intervals or require manual transcription; in this case we can not guarantee regular updates.
We do intentionally refrain from using any interpretative elements - such as thresholds or advisories. This needs to happen somewhere else with more competent people involved.
Measurements are interchangeably provided in Grey/Sievert units at the source. Here all measurements are given in the nano Sievert/hour (nSv/h) measure - following the simplified equation where 1 Grey (Gy) = 1 Sievert (Sv).
This map visualises crowd-sourced radiation geiger counter readings from across Japan. Click on the labels to get more information on the source of each reading.
The number of locations fluctuate due to the validity of the data feeds. There are approximately 185 feeds from the official Japanese government source MEXT and the rest are from other sources such as the Tokyo hackspace, universities,local councils and concerned individuals.