The Great Kantō Earthquake

The Great Kantō earthquake was one of the worst natural disasters in Japanese history. It caused widespread damage in Tokyo, Yokohama, the surrounding prefectures of Chiba, Kanagawa, and Shizuoka, and throughout the Kantō region. The estimated deaths brought about by the Great Kantō earthquake tragedy reached about 142,800.

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Destruction caused by the Great Kantō earthquake.

On a busy Saturday, September 1, 1923, at 11:58am, the initial shock of an earthquake with a magnitude of 7.9 Mw (moment magnitude scale, a successor to the Richter Scale that measures earthquake size by energy released), struck Japan. It is now known throughout history as the Great Kantō earthquake. It was caused by a rupture of part of the convergent boundary of an actively deforming region, where two (or more) tectonic plates collided: the Philippine Sea Plate moved under the Okhotsk Plate along the Sagami Trough. Based on accounts, the earthquake was said to have lasted anywhere between four and ten minutes and within minutes of the initial shock caused a tsunami with waves that were as high as 40 feet. The series of towering waves swept away thousands of people into the ocean.

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Marunouchi district after the Great Kanto Earthquake.

The Great Kantō earthquake struck midday when many people were busily going about preparing lunch over the fire. As a result, fires broke out and developed into firestorms that swept across the cities. The fires were so extreme that they melted the tarmac and caused the feet of fleeing people to get stuck. The catastrophic event’s single greatest loss of life was a fire tornado that engulfed the former Army Clothing Depot, Rikugun Honjo Hifukusho, in downtown Tokyo. It took nearly two whole days for the fires to be put out. To make things worse, a typhoon struck Tokyo Bay at the same time. The strong winds of the typhoon caused the fires to spread rapidly off the coast of Noto Peninsula in Ishikawa Prefecture.

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View from Kotobuki Junior School in Yokohama.

To commemorate the tragic event, September 1 is designated as Disaster Prevention Day to remind people to always be prepared, especially during the months of typhoon season. Memorials are located in Yokoamicho Park in Sumida ward where thousands of people were killed during the fire tornado.