1923 Great Kantō earthquake collapsed due to urbanization. The 1923 earthquake led to record-high morbidity due to unsanitary conditions following the earthquake, and it prompted the establishment of antityphoid measures and the building of urban infrastructure. The Honda Point Disaster on the United States west coast, in which seven US Navy destroyers ran aground and 23 lives were lost, has been attributed to navigational errors caused by unusual currents set up by the earthquake in Japan. Beginning in 1960, every September 1 is designated as Disaster Prevention Day to commemorate the earthquake and remind people of the importance of preparedness, as August and September
Imperial Japanese Navy Air Service and the first one to be completed as from the keel up. In the 1920s, the larger percentage of aircraft that were initially acquired and inducted into service, were land based seaplanes whose main tasks were reconnaissance and anti-submarine patrols. The Japanese had drawn up plans for the formation of 17 squadrons of these aircraft, but budgetary constraints limited the units to eleven until 1931. Under the terms of the Washington Naval Treaty two incomplete capital ships were allowed to be rebuilt as carriers, for the Japanese; and . However, "Amagi" was damaged during the Great Kanto earthquake in 1923