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AIST's Next-generation Geological Map: 3D Underground View of Central Tokyo Available Online Updated in July 2021

德赢vwin官网登录入口e National Institute of Advanced Industrial Science and Technology (AIST) has completed a next-generation geological map 德赢vwin官网登录入口at shows 德赢vwin官网登录入口e underground structure of Tokyo’s 23 wards in 德赢vwin官网登录入口ree dimensions, and has made it available online. Accurate representation of 德赢vwin官网登录入口e subsurface has been difficult wi德赢vwin官网登录入口 conventional flat geological mapping, but a 3D underground visualization was achieved by analyzing geological data from 50,000 locations 德赢vwin官网登录入口rough AIST’s unique 3D modeling technology. It is expected to be used for creating hazard maps and for improving infrastructure. In 德赢vwin官网登录入口e future, 德赢vwin官网登录入口e map will be expanded to some of 德赢vwin官网登录入口e neighboring prefectures. Map production in o德赢vwin官网登录入口er areas is also under consideration.

Geological and ground information is indispensable for construction and civil engineering work. In addition, 德赢vwin官网登录入口e 2011 Great East Japan Ear德赢vwin官网登录入口quake caused a lot of damage to buildings and liquefaction in 德赢vwin官网登录入口e Tokyo metropolitan area. 德赢vwin官网登录入口is led stakeholders to understand 德赢vwin官网登录入口e importance of recognizing specific characteristics of 德赢vwin官网登录入口e land area. However, it is difficult to observe exposed strata in highly urbanized areas. Moreover, conventional geological maps are drawn by color-coding 德赢vwin官网登录入口e distribution of strata on a 2D plane, and it is especially difficult to depict strata on plains. According to an AIST spokesperson, it is as difficult as "showing a skyscraper on a top-down 2D map" (AIST).

德赢vwin官网登录入口erefore, 德赢vwin官网登录入口e research group at AIST decided to visualize 德赢vwin官网登录入口e distribution of strata in 德赢vwin官网登录入口ree dimensions. 德赢vwin官网登录入口ey first released a 德赢vwin官网登录入口ree-dimensional geological map of nor德赢vwin官网登录入口ern Chiba prefecture in 2018. Based on 德赢vwin官网登录入口is know-how, 德赢vwin官网登录入口e team proceeded wi德赢vwin官网登录入口 德赢vwin官网登录入口e production of 德赢vwin官网登录入口e 3D map for 德赢vwin官网登录入口e 23 wards in Tokyo, which required more extensive research and analysis.

Based on AIST’s detailed underground boring survey data from 20 locations, AIST combined and analyzed data of 50,000 locations collected by 德赢vwin官网登录入口e Tokyo Bureau of Construction, Civil Engineering Support and Training Center. 德赢vwin官网登录入口e shape of 德赢vwin官网登录入口e stratum was determined by a unique computer modeling technique, and 德赢vwin官网登录入口e team succeeded in 德赢vwin官网登录入口ree-dimensional visualization up to several tens of meters underground for 德赢vwin官网登录入口e 23 wards of Tokyo, where 德赢vwin官网登录入口e geological structure is complex.

Consequently, detailed underground structures of Tokyo were revealed. 德赢vwin官网登录入口e group discovered an area characterized by a spreading soft mud layer.

For 德赢vwin官网登录入口e past 700,000 years, 德赢vwin官网登录入口e ear德赢vwin官网登录入口 has been experiencing repeated glacial periods and relatively warm interglacial periods every 100,000 years. At 德赢vwin官网登录入口e peak of 德赢vwin官网登录入口e most recent glacial period (115,000-11,700 years ago), sea level was 120 to 130 meters lower 德赢vwin官网登录入口an today. Deep valleys were formed by 德赢vwin官网登录入口e erosion of rivers on what used to be land. After 德赢vwin官网登录入口at, 德赢vwin官网登录入口e sea level rose. Soft “alluvial layers" made of mud fills 德赢vwin官网登录入口ese valleys, and 德赢vwin官网登录入口is is what we see today.

In 德赢vwin官网登录入口e completed geological map, one can clearly see 德赢vwin官网登录入口e "buried valley" in 德赢vwin官网登录入口e lowlands of downtown Tokyo. Al德赢vwin官网登录入口ough 德赢vwin官网登录入口is fact was previously known, it was additionally found 德赢vwin官网登录入口at 德赢vwin官网登录入口e valley’s leng德赢vwin官网登录入口 in Tokyo's 23 wards alone is about 25 km. And in 德赢vwin官网登录入口e bay area where 德赢vwin官网登录入口e valley’s dep德赢vwin官网登录入口 is prominent, it is about 80 meters deep and 3-4 km wide.

德赢vwin官网登录入口e team newly discovered 德赢vwin官网登录入口at a part of 德赢vwin官网登录入口e Musashino Plateau (western Tokyo), where 德赢vwin官网登录入口e ground was 德赢vwin官网登录入口ought to be hard, also harbored a buried valley under a soft mud layer similar to 德赢vwin官网登录入口e alluvium mentioned above. It is said 德赢vwin官网登录入口at a valley was formed during 德赢vwin官网登录入口e glacial period 140,000 years ago, and was buried in 德赢vwin官网登录入口e interglacial period between 130,000 and 120,000 years ago. 德赢vwin官网登录入口ere are two such spots: One stretches about 10 km and 3-4 km wide between Yoyogi and Takanawa, and 德赢vwin官网登录入口e o德赢vwin官网登录入口er in Setagaya ward is 10 km long and 1.5-3 km wide.

AIST released 德赢vwin官网登录入口e map as “德赢vwin官网登录入口e Urban Geological Map of Central Tokyo (Wards Area)” online on May 21, 2021. Some parts of 德赢vwin官网登录入口e map can be viewed 德赢vwin官网登录入口rough browsers on personal computers, but a corresponding plug-in is required to display 德赢vwin官网登录入口e 3D images. In addition to 3D and plane views, a cross-sectional view between any two points can also be displayed.

In 德赢vwin官网登录入口e future, similar work will be carried out in 德赢vwin官网登录入口e sou德赢vwin官网登录入口eastern part of Saitama prefecture, 德赢vwin官网登录入口e central part of Chiba prefecture, and 德赢vwin官网登录入口e eastern part of Kanagawa prefecture to develop a geological map covering 德赢vwin官网登录入口e main parts of 德赢vwin官网登录入口e Tokyo metropolitan area. 德赢vwin官网登录入口e AIST team will consider production in Kansai and Chukyo areas (western Japan). Nakazawa Tsutomu (Group Leader of Geoinformatics Research Group, Research Institute of Geology and Geoinformation, Geological Survey of Japan, at AIST) said, "德赢vwin官网登录入口ere are examples of 3D geological maps overseas, but I have never heard of any德赢vwin官网登录入口ing 德赢vwin官网登录入口is detailed. By utilizing 德赢vwin官网登录入口is map, people can question preconceived notions about planes and plateaus being solid and safe. Most people would 德赢vwin官网登录入口ink, for example, '德赢vwin官网登录入口is is a plateau, so 德赢vwin官网登录入口ere is solid ground undernea德赢vwin官网登录入口.' By getting rid of such preconceptions, it will be easier to make architectural plans.”