The Safecast project was started as a reaction to the March Eleventh 2011 Earthquake in Japan and the nuclear accident at Fukushima. This grassroots project attempted to gather independent radiation levels to double check the information released by the government.
The maps are compiled using data from driving around by car, handheld devices and a growing network of connected sensors. This project was successfully funded through kickstarter.
The Safecast Map depicts over 600,000 radiation data points collected by the Safecast team throughout Japan. For each square, numerous geiger readings have been collected and color-coded. For detailed maps showing all data points, please visit the Drive Maps page.
As part of their efforts to get readings for all of Japan, including many areas that have never had published measurements, they’ve been driving across the country taking readings constantly as they go. This provides some exceptionally detailed mapping of radiation levels along the routes we have traveled, which they Safecasting.