Shortly before noon on September 1, 1923, an earthquake measuring 7.9 on the Richter scale sent shockwaves through the Tokyo-Yokohama metropolitan area. The violent tremors left few buildings habitable and prompted a tsunami that surged up to 40 ft. (12 m.) high. But the damage continued for days: by the time the fires stemming from the quake were contained, 90% of Yokohama's buildings were reportedly damaged or in ruins, and some two-fifths of Tokyo's had been destroyed — leaving half its population homeless. Nearly 143,000 people died.