What is a fiction technique used in "A Noiseless Flash" by John Hersey, and what are its effects?

"A Noiseless Flash" is the first chapter in John Hersey's Hiroshima, a narrative re-telling of the atomic bomb blast on Hiroshima in August of 1945. It was first published in The New Yorker magazine. 

Hersey tells the story of the destructiveness of the blast in a narrative way, starting on the calm morning before the blast. He provides detailed descriptions of each of the six characters he will follow throughout the book as they...

"A Noiseless Flash" is the first chapter in John Hersey's Hiroshima, a narrative re-telling of the atomic bomb blast on Hiroshima in August of 1945. It was first published in The New Yorker magazine. 

Hersey tells the story of the destructiveness of the blast in a narrative way, starting on the calm morning before the blast. He provides detailed descriptions of each of the six characters he will follow throughout the book as they deal with the bomb's detonation and its aftermath. The characters are two doctors, a Catholic priest, a seamstress, a reverend, and a factory worker. He describes the morning activities of these characters in the type of detail a novelist might use, as the mundane and humdrum nature of their morning is forever disturbed by the bomb. As Hersey writes about the experience of the reverend:

"There was no sound of planes. The morning was still; the place was cool and pleasant. Then a tremendous flash of light cut across the sky. Mr. Tanimoto has a distinct recollection that it travelled from east to west, from the city toward the hills. It seemed a sheet of sun."

The fictional techniques that Hersey uses are setting up the paradox of the calmness of the blast. There is no loud noise; instead, the flash of the bomb is quiet and still, and there are no planes. The paradox is that the bomb is very destructive but destroys in an almost peaceful-seeming way. Another fictional device he uses is the presentation of many characters, as he alternates between their stories. The effect of using these fictional techniques is to heighten the already tense drama of the story and to express its human impact.