Earthquake Rocks Japan Summary

  • Last updated on November 10, 2022

After Japan experienced one of the most destructive earthquakes in history, building codes were improved and modern architectural standards were established.

Summary of Event

On September 1, 1923, an earthquake that would have registered a magnitude 8.3 on the modern Richter scale shook the heavily populated Japanese cities of Yokohama and Tokyo on the island of Honshū. Often called the great Kanto earthquake because it affected cities on the Kanto Plain, the quake is remembered as among the most costly natural disasters in history. Scientists have estimated that it created a shock wave three hundred times more powerful than that produced by the atomic bomb that devastated Hiroshima in 1945. Earthquakes;Japan Geology;earthquakes Disasters;earthquakes Urban planning Building codes Great Kanto earthquake [kw]Earthquake Rocks Japan (Sept. 1, 1923) [kw]Japan, Earthquake Rocks (Sept. 1, 1923) Earthquakes;Japan Geology;earthquakes Disasters;earthquakes Urban planning Building codes Great Kanto earthquake [g]East Asia;Sept. 1, 1923: Earthquake Rocks Japan[05850] [g]Japan;Sept. 1, 1923: Earthquake Rocks Japan[05850] [c]Disasters;Sept. 1, 1923: Earthquake Rocks Japan[05850] [c]Earth science;Sept. 1, 1923: Earthquake Rocks Japan[05850] [c]Urban planning;Sept. 1, 1923: Earthquake Rocks Japan[05850] Gotō Shimpei

The Japanese archipelago is located within the “Pacific Ring of Fire,” Pacific Ring of Fire a narrow zone of tectonic activity and volcanoes surrounding the Pacific Ocean. Volcanoes;Pacific Ring of Fire About 80 percent of the world’s earthquakes take place within this area. Japan experiences about three thousand tremors each day and averages one large earthquake every seventy years. Before 1923, the most serious Japanese quakes were the Hizen earthquake on February 10, 1792, which resulted in the deaths of fifteen thousand people, and the Sinano earthquake on May 8, 1844, which killed twelve thousand.

The morning of September 1, 1923, was warm, with wind gusts followed by rain. When the quake struck at 11:58 a.m., many residents of Yokohama and Tokyo were busy preparing their midday meals. The quake’s epicenter was located about fifty miles southwest of Tokyo Bay in an area called the Sagami Trough. Within this region, the northeastern edge of the Philippine Sea plate converges with the southeastern edge of the Eurasian plate. The ground shaking associated with the initial shock lasted five minutes. The quake was registered in Hawaii, Washington, D.C., and northern Great Britain.

It has been estimated that more than fifteen thousand people were killed in the first two minutes of the quake, as buildings toppled and loose debris fell. In Yokohama’s harbor, the shaking caused liquefaction of soil material, damaging buildings and other structures. Elsewhere, shock waves produced hundreds of landslides and mudflows, especially along the Boso and Miura Peninsulas. One mudflow buried the entire village of Nebukawa. The entire Boso Peninsula was tilted toward the northeast and uplifted, in some places as much as six feet. In addition to collapsing homes and office buildings, the force of the quake displaced roads and railroad tracks. In Kamakura the quake tore the Great Buddha statue from its foundation. In addition to damage caused by shaking, shock waves produced a tsunami Tsunamis wave thirty-nine feet high that struck the north shore of Oshima and was felt as far away as Ecuador in the eastern Pacific Ocean. Hundreds of smaller tremors were felt in the hours after the initial quake.

After the quake, numerous fires, many ignited by overturned cooking ranges, burned uncontrollably in Tokyo and Yokohama. In Yokohama more than eighty separate fires swept through areas with tightly packed wood and paper houses. The wind, which was blowing at speeds up to eighteen miles per hour, became a major obstacle to containing the flames. More than thirty thousand people fleeing the firestorm in Tokyo’s Fukagawa and Honjo neighborhoods were forced into open areas that offered little refuge from the flames and heat. Many perished in wind-spawned cyclones. Emergency responders seeking to extinguish fires could do little because the quake had broken water mains. In Yokohama Harbor, leaking oil caught fire the morning after the quake. Many fires continued to burn until September 3, and afterward it was difficult to distinguish regions devastated by the quake from those destroyed by fire.

Thousands died while trapped inside collapsed structures. More than forty thousand persons who fled to the Military Clothing Depot died when a firestorm devastated the building. Survivors described the flames as sounding like heavy surf with occasional thunderous crashes. The total number of dead has been estimated at more than one hundred thousand, with forty thousand others missing. Even in rural areas, where fewer buildings were destroyed than in the cities, more than twelve thousand people died.

Panic in the aftermath of the quake led to rumors that Koreans living in the region had set fires, poisoned water sources, and looted homes. As a result, civilian militias killed thousands of Koreans. On September 8, Tokyo was placed under martial law and the army was given responsibility for distributing food, seizing property, and taking other actions needed to maintain order. Engineering corps worked night and day to repair roads, bridges, and communications facilities.

Seven prefectures were affected by the quake: Tokyo, Kanagawa, Saitama, Ibaraki, Shizuoka, Chiba, and Yamanashi. Most people in these areas were without information about the magnitude of destruction or the status of friends and relatives. Damaged telephone and telegraph lines isolated survivors from the outside world. The first news reports about the quake were transmitted by radio from ships anchored in Yokohama and Tokyo Bays. In the absence of functioning newspapers, signs were posted to coordinate relief efforts and share information about missing persons.

Nearly seven hundred thousand homes were completely or partially destroyed in the affected areas, leaving almost two million persons homeless. In addition to severe damage to buildings, many other structures—such as tunnels, storage tanks, canals, sewers, and dams—were destroyed or damaged by the quake and subsequent fires. Twisted train tracks and rubble left in the streets made road travel nearly impossible. A few buildings did escape damage, however. The Royal Palace was spared because of its thick walls and water-filled moat. Concrete and steel-reinforced structures, such as the headquarters of the Mitsubishi Corporation and the Nippon Kogyo Building, experienced only minor damage.

In the weeks after the quake, severe damage to businesses—including facilities in Yokohama’s port—caused the unemployment rate to soar. Damage to farms and warehouses brought requests for immediate international assistance. Gotō Shimpei, Tokyo’s mayor, organized the rebuilding of the city. An emergency requisition ordinance was implemented to allow government officials to obtain any goods needed in the relief effort. The Japanese government set aside ten million yen to assist with the relief effort, and monetary support for rebuilding damaged areas came from countries around the world.


The devastation of the Kanto earthquake served as a catalyst for the development of improved engineering to minimize future earthquake-related damage. In 1929, the World Engineering Congress held a conference in Tokyo with earthquake construction Earthquake construction as a central topic. Attendees introduced designs for buildings that would be resistant to wind forces but remain flexible during seismic events.

Basic building codes were substantially changed in Japan following the quake. Many one- and two-story buildings made out of wood or brick were replaced with modern five- and six-story structures of concrete and steel. New parks and open areas were planned throughout Tokyo as places where citizens could take refuge in the event of an earthquake.

The process of rebuilding began slowly, but it built momentum significantly after 1926. An underground rail system was introduced in 1927 and a new airport in 1931. By 1932, Yokohama and Tokyo were again bustling urban areas, and by 1935 the population of Tokyo was larger than it had been before the quake. The new emphasis on designing structures to withstand severe earthquakes did not carry over into a concern for preventing fire damage, however, and many of the structures built in Tokyo and Yokohama after the quake were made with flammable materials. As a result, a large number of structures in these areas were burned in Allied bombing raids during World War II.

Although the Kanto earthquake was not the largest ever to strike Japan, its proximity to cities with combined populations of more than two million made it among the most costly natural disasters in history. The earthquake was responsible for one of the two largest peacetime fires in modern history, the other being the fire caused by the 1906 San Francisco earthquake. Few buildings that stood in Yokohama and Tokyo before the 1923 quake remain today. Among its long-term impacts, the earthquake raised awareness throughout Japan and the world about the importance of disaster management. Since 1960, September 1 has been designated Disaster Prevention Day in Japan, and each year on that date private and public organizations sponsor disaster preparation drills. Earthquakes;Japan Geology;earthquakes Disasters;earthquakes Urban planning Building codes Great Kanto earthquake

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Busch, Noel F. Two Minutes to Noon. New York: Simon & Schuster, 1962. Presents a historical account of the 1923 quake based on extensive research conducted in Japan.
  • citation-type="booksimple"

    xlink:type="simple">Clancey, Gregory. Earthquake Nation: The Cultural Politics of Japanese Seismicity, 1868-1930. Berkeley: University of California Press, 2006. Focuses on social issues tied to earthquakes in Japanese life.
  • citation-type="booksimple"

    xlink:type="simple">Ryang, S. “The Great Kanto Earthquake and the Massacre of Koreans in 1923: Notes on Japan’s Modern National Sovereignty.” Anthropological Quarterly 76, no. 4 (2003): 731-748. Examines issues associated with the deaths of nearly six thousand Koreans as a result of the earthquake, fires, and subsequent killings.
  • citation-type="booksimple"

    xlink:type="simple">Utsu, T. “Japanese Earthquakes 1885-1925.” Bulletin of the Earthquake Research Institute 57 (1982): 111-117. A technical look at the large earthquakes that affected Japan in the late nineteenth and early twentieth centuries.

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