Why was destruction in Nagasaki limited by the city’s terrain?

The destruction caused by the atomic bomb dropped on Nagasaki was limited by the city’s uneven, hilly terrain, which acted as a natural shield against the blast's effects.12

Unlike the relatively flat landscape of Hiroshima, which allowed for widespread firestorm damage, Nagasaki’s urban area was divided into two coastal valleys separated by a range of hills. Because the bomb detonated over the Urakami Valley, the surrounding hills obstructed the shockwaves and thermal radiation from reaching other parts of the city. Consequently, while the weapon was significantly more powerful than the one used on Hiroshima, a substantial portion of Nagasaki—particularly in the southeastern industrial and government districts—remained relatively unscathed.2314