September 1 marks the 100th anniversary of the Great Kanto Earthquake, which caused unprecedented damage in Tokyo and surrounding areas. Reconstruction projects laid the foundation for cities in the Tokyo metropolitan area. Measures such as earthquake-proofing and non-combustibility of buildings continue to this day based on lessons learned, and disaster prevention and mitigation activities are being expanded based on the experience of the Great Hanshin and Great East Japan Earthquakes.
The Great Kanto Earthquake occurred at 11:58 a.m. on September 1, 1923, and recorded 7.9 magnitude with its epicenter in the Sagami Trough, causing damage over a wide area from mountainous regions to populated areas around Tokyo Bay. The direct death toll was 105,385 and the economic damage reached approximately 5.5 billion yen, more than three times the national budget at the time. Kanagawa Prefecture had the largest number of collapsed houses, while Tokyo had the largest number of fire deaths and burned buildings, although some areas were less shaken than others. Approximately 90% of the deaths in Tokyo were due to fires. Liquefaction, tsunami and landslides also occurred in Chiba and Saitama.
Reconstruction after the earthquake was led by the then Reconstruction Agency. Projects based on the reconstruction plan have led to the formation of the current urban infrastructure and streetscapes. Projects such as Yamashita Park in Yokohama, a plaza reclaimed from rubble, and the first concrete apartment complexes were built. In 1924, the year after the earthquake, the world's first seismic regulations were enacted in the Urban Building Law (predecessor to the Building Standards Law) to make buildings earthquake-resistant, and in 1925 the Earthquake Research Institute was established at Tokyo Imperial University (now Tokyo University), leading to full-scale earthquake research activities.
The 2023 edition of the "White Paper on Disaster Management," approved by the Cabinet on June 16, 2023, opens with a special feature to mark the 100th anniversary of the Great Kanto Earthquake. To look back at the time of the earthquake, the Cabinet Office gathered the necessary details from over 600 pages of reports by government expert study groups and the results of various surveys. By analyzing a variety of data, it summarized the history of disaster prevention from the earthquake and the challenges of today's changing society and economy, and presented the direction of future disaster prevention based on lessons learned from the past. (2023/08/25)