Tokyo (1923-1924) I Great Leap after the Great Kanto Earthquake
Being regarded as the second most exposed city in the world for natural disasters, Tokyo consists of 87% of earthquake resistant buildings, including high-rises and skyscrapers. The great leap in earthquake resistant measures and technologies can be attributed to the Great Kanto Earthquake in 1923, which is one of the deadliest earthquakes in Tokyo. Measuring 7.9 on the Richter scale deliver shockwaves through Tokyo-Yokohama metropolitan area, the earthquake destroyed more than 45% of buildings in Tokyo – pushing half of its population to homeless and causing 143, 000 people of death [figure 1], as well as reflecting whether the current building ordinance was comprehensive enough to reduce the damage.
Figure 1 – Kanda Ogawamachi, after the Great Kanto Earthquake (Source from Oldtokyo.com)
After the devastating earthquake, there was building law amendments concerning the seismic requirements which were not required before, as well as legal qualification of design architects and engineers. Right after the earthquake, fire was one of the most life-threatening issues since more than 45% of land in Tokyo was in fire [figure 2]. This triggered the implementation of avoiding catching fire from outside, as well as outbreak and spread among the buildings.
Figure 2 – Map of the burnt area after the Great Kanto Earthquake
(Source from Urban planning for disaster resilient cities in case of Japan)
Also, there is revised seismic codes in 1924 which required structural calculation in considering seismic force, as well as amended the seismic coefficient (Ishiyama, 2011). It was a significant amendment since it was not only the first such requirement in Japan, but also in the world, revealing the emphasis on the harms of earthquake and importance of laying down building regulations. The revision of Urban Building Law was also to increase the size of wooden columns and specify the length of lap joints of reinforcing bars on wooden and reinforced concrete buildings respectively.
Apart from the impacts on the regulations on individual buildings, there was influences on city planning strategies since as a tabula rasa, Tokyo was regarded as an opportunity to implement urbanism principles that would helped rearrange the chaos in Tokyo. Rejecting the ambitious city planning ideas, Goto Shinpei, mayor of Tokyo, planned to treat the reconstruction as a national project, rather than an experiment of innovative ideas (Hein, 2005). Land utilization plan and land rezoning project were introduced as a system for the coming urban development [Figure 3]. His goals were to refuse the relocation of the capital, make use of advanced Western planning techniques, control independent building activities of landowners and achieve a rational road network (Sorensen, 2005). Land readjustment and residential recovery and construction were carried out in order to tackle with disorder and blurry boundaries among the city. Some districts such as the Shitamachi areas were fully renovated due to severe damage (BCPTMG, 2004).
Figure 3 – Map of land utilization plan and land rezoning project (Source from 東京市役所)
As one of the most influential event in Tokyo, the Great Kanto Earthquake not only brought devastating impacts to the city, but also turned the city into a new chapter which was able to tackle with natural disasters wisely, as well as modernize the city and resume back to peace. Legislatively, it reinforced the quality and standardized the new buildings in the future, and reformed the city order and urban fabric.
 Ishiyama, Y. 2011. Introduction to Earthquake Engineering and Seismic Codes in the World. Hokkaido University.
 Hein, C. 2005. Resilient Tokyo : Disaster and transformation in the Japanese City. Oxford University Press.
 Sorensen, A. 2005. The Making of Urban Japan: Cities and Planning from Edo to the Twenty First Century. Routledge.
 Bureau of City Planning Tokyo Metropolitan Government (BCPTMG). 2004. Transition in City Planning in Tokyo.