If it were 100 megatons it would have leveled the forest of Germany all the way to Rome. The fireball alone would be 200 miles across.
The most likely cause was a low-density comet, 0.7 miles (1.1 kilometres) wide, that broke up at an altitude of 43 miles and fell in pieces to Earth, the scientists reported in Astronomy Magazine.
They wrote: The main mass of the projectile struck the ground at 2,200 miles per hour, releasing an amount of energy equivalent to 106 million tons of TNT.
The bomb that destroyed Hiroshima at the end of the Second World War had an explosive force of just 20,000 tons of TNT.
Wrong, the entire cloud created from a 100 megaton explosion would be about 120km across. 200 mile fireball ?? No way, but the thermal pulse might be felt that far.