On Friday 11 March 2011 a 9.0-magnitude undersea earthquake off the coast of Japan caused crippling damage to nuclear reactors at the Fukushima I and II Nuclear Power Plant in Ōkuma. Fears of significant radiation leaks led to a massive evacuation for over 45,000 people in the area.
Japan has released some data about radioactivity levels around the Fukushima nuclear plants.
I reinterpreted the original chart into a heat map using Excel. Using large “bubbles” and a gradient colour scheme I emphasized each data point and showed how radiation “cools” as time goes by in this Excel chart.