Photo/Illutration The shadows of a parapet created by heat rays on what is now known as the Nishi-heiwa-ohashi bridge, 620 meters from the blast center of the atomic bombing of Hiroshima. This photo was taken by Kiyoshi Kanai or Toshio Maeda on Nov. 6, 1945, and donated by Kazuyoshi Kudo. (Provided by the Hiroshima Peace Memorial Museum)

HIROSHIMA--The Hiroshima Peace Memorial Museum next fiscal year will display previously unseen photographs and scientific materials left by a seismologist who surveyed Hiroshima and Nagasaki immediately after the 1945 atomic bombings.

The materials were kept by the bereaved family of Kiyoshi Kanai, a former vice president of Nihon University who was among the first to estimate the blast center of the atomic bomb in Hiroshima.

“The materials are precious because they record detailed circumstances at the time,” a museum representative said.

Some of the 255 photographs and records donated to the museum were shown to reporters on Oct. 17.

According to the museum, Kanai, who was born in Hiroshima in 1907, was an engineer at the earthquake research institute of Tokyo Imperial University (now the University of Tokyo) when the U.S. atomic bombs detonated over Hiroshima and Nagasaki in August 1945.

At the education ministry’s instruction, Kanai visited Hiroshima immediately after the blast for research purposes and was exposed to radiation.

He also went to Hiroshima and Nagasaki between October and November 1945 and in January 1946 to examine structural damage and the directions of shadows created by heat rays on buildings and bridges. From those studies, he estimated the location of ground zero in the cities as well as the detonation heights of the bombs.

The donated materials include a draft report that estimates the detonation height at 570 meters over Hiroshima, with a margin of error of plus or minus 20 meters. The latest research put the explosion at about 600 meters above the city.

Also donated were a research diary and photos with the dates, times, places, directions of the shot, shutter speeds and other data on the backs.

Kanai, who served as a professor at the Earthquake Research Institute of the University of Tokyo and president of the predecessor of the Seismological Society of Japan, won the Asahi Prize in fiscal 1976 for his scientific achievements.

However, he was concerned about the possible effects of radiation from the blasts on his health. In his book published in 1995, Kanai wrote, “At some point in life, I thought my life may end tomorrow, so I seriously developed a research plan on the assumption that I would live until 50.”

Kanai died in 2008 at the age of 100.

“Kanai must have felt fear even during his inspections,” said Hironobu Ochiba, a curator at the museum. “He risked his life to visit Hiroshima, likely because he wanted to accurately record the devastation of his hometown for posterity.”

Kanai’s bereaved family presented the materials to Kazuyoshi Kudo, a seismic engineering professor at Nihon University and a friend of Kanai. Kudo donated the materials to the museum in November last year.