Aftermath: the devastation of Hiroshima in 1948, three years after the atomic bomb was dropped (AFP/Getty) / AFP/Getty

As well as the horror of the Little Boy bomb dropped on Hiroshima, app shows the true scale of the atomic weapons that are in our current armoury

It’s difficult to imagine the scale of destruction that was wrought on Hiroshima 70 years ago, when a hugely-powerful nuclear bomb was dropped on it from an American plane. But one app lets people try envisioning it, mapping out the scale of the destruction on the place where they live.

Nukemap, developed by historian of science Alex Wellerstein, simulates the blast and fallout of a nuclear bomb, allowing people to see the full scale of the atomic bomb. The map can plot the fallout area on any location, allowing people to see the destruction a similar bomb — or the more powerful ones being developed today — would bring to their home.

On the app, users can select from a range of locations (including Hiroshima and Nagasaki) and preset bombs (like Little Boy and Fat Man, which were dropped on Japan). They can then choose how exactly the bomb should be dropped and detonated, before seeing the effects plotted on a map and the casualties counted up.

A similar tool has been developed by PRI, which shows just the effects of the Hiroshima bombing, transposed to any location.

About 75,000 people were killed by the bomb on Hiroshima, dropped on August 6, 1945. Another 70,000 were injured ,and much of the city was completely levelled.