Question
Following the Tokyo Metro Tozai Line from west to east, how do the seismic, flood, landslide and overall scores returned by DisasterShield line up? The points are the 17 Tozai Line stations that lie inside Tokyo's ward area.
Method
- Product and screen: DisasterShield,
/try. It has a latitude field, a longitude field and a 「スコア取得」 (get score) button; there is no address search. - Inputs: the latitude and longitude of each station, to 5 decimals. Each point is the centroid of the station's line geometry in the National Land Numerical Information railway data (2025 edition): the length-weighted mean of the segment midpoints, then rounded. It is not the position of an entrance or a station building. The dataset gives station names in Japanese; the romanised names in this note are the author's transliteration.
- Which stations: of the 23 stations whose operator is 「東京地下鉄」 and whose line name is 「5号線東西線」 in that data, the 17 whose point falls inside one of the ward polygons of the boundary file (derived from dataofjapan/land). The other 6 (Urayasu, Minami-Gyotoku, Gyotoku, Myoden, Baraki-Nakayama, Nishi-Funabashi) fall outside the polygons and were left out.
- Accuracy of the boundary file: we did not verify the accuracy of this ward boundary file. We therefore computed, on the same file, each station's distance to the outer edge of the ward area to see whether any station is close to it. Only Urayasu was closer than 500 m (469 m, outside, already excluded); the closest included station is Nishi-Kasai at 1179 m.
- The product's own coverage test: DisasterShield returns scores only when the entered point intersects one of the special wards in the National Land Numerical Information administrative area data (N03-20250101). We repeated the same test offline with the same distribution file and confirmed that all 17 stations are inside.
- Recording: one score request per station; the 4 score cards and the 「スコア粒度(地震)」 (seismic score granularity) box were recorded as displayed.
- Date and production revision: 2026-10-13. Cloud Run revision
disastershield-00028-vv5(commit50e60ea). The results are the output of the production revision at that time.
How the scores are computed was confirmed by reading the code at that commit.
- Seismic: a value loaded from J-SHIS (the product treats it as a seismic intensity) is mapped to a score along a piecewise-linear curve through 4.5 → 10, 5.0 → 30, 5.5 → 50, 6.0 → 70, 6.5 → 85, 7.0 → 100.
- Which cell is read: the nearest loaded cell within 1500 m of the entered point. According to the loader's own description, what is loaded are 250 m cells sampled on a 0.01-degree lattice.
- Flood: the deepest depth rank among the flood inundation polygons that contain the point is mapped to one of 25, 50, 70, 85, 95, 100. With no containing polygon the score is 5.0.
- Landslide: 65 if the point is in a warning area, 90 if it is in a special warning area, 5.0 otherwise.
- Overall: 0.5 × seismic + 0.3 × flood + 0.2 × landslide.
- No building attribute is used: only the latitude and longitude reach the score calculation.
Results
Coordinates entered, west to east.
| Station | Latitude | Longitude |
|---|---|---|
| Nakano (中野) | 35.70574 | 139.66560 |
| Ochiai (落合) | 35.71063 | 139.68597 |
| Takadanobaba (高田馬場) | 35.71328 | 139.70504 |
| Waseda (早稲田) | 35.70568 | 139.72219 |
| Kagurazaka (神楽坂) | 35.70387 | 139.73452 |
| Iidabashi (飯田橋) | 35.70140 | 139.74652 |
| Kudanshita (九段下) | 35.69609 | 139.75127 |
| Takebashi (竹橋) | 35.69044 | 139.75767 |
| Otemachi (大手町) | 35.68470 | 139.76603 |
| Nihombashi (日本橋) | 35.68238 | 139.77410 |
| Kayabacho (茅場町) | 35.68035 | 139.77927 |
| Monzen-nakacho (門前仲町) | 35.67189 | 139.79610 |
| Kiba (木場) | 35.66936 | 139.80712 |
| Toyocho (東陽町) | 35.66959 | 139.81768 |
| Minami-sunamachi (南砂町) | 35.66841 | 139.83169 |
| Nishi-kasai (西葛西) | 35.66456 | 139.85960 |
| Kasai (葛西) | 35.66362 | 139.87253 |
Score cards as displayed (each out of 100).
| Station | Seismic | Flood | Landslide | Overall |
|---|---|---|---|---|
| Nakano (中野) | 73.0 | 5.0 | 5.0 | 39.0 |
| Ochiai (落合) | 73.0 | 25.0 | 5.0 | 45.0 |
| Takadanobaba (高田馬場) | 70.0 | 25.0 | 5.0 | 43.5 |
| Waseda (早稲田) | 70.0 | 25.0 | 5.0 | 43.5 |
| Kagurazaka (神楽坂) | 70.0 | 5.0 | 5.0 | 37.5 |
| Iidabashi (飯田橋) | 76.0 | 50.0 | 5.0 | 54.0 |
| Kudanshita (九段下) | 76.0 | 25.0 | 5.0 | 46.5 |
| Takebashi (竹橋) | 76.0 | 25.0 | 5.0 | 46.5 |
| Otemachi (大手町) | 73.0 | 50.0 | 5.0 | 52.5 |
| Nihombashi (日本橋) | 73.0 | 25.0 | 5.0 | 45.0 |
| Kayabacho (茅場町) | 73.0 | 50.0 | 5.0 | 52.5 |
| Monzen-nakacho (門前仲町) | 79.0 | 50.0 | 5.0 | 55.5 |
| Kiba (木場) | 79.0 | 50.0 | 5.0 | 55.5 |
| Toyocho (東陽町) | 82.0 | 70.0 | 5.0 | 63.0 |
| Minami-sunamachi (南砂町) | 82.0 | 50.0 | 5.0 | 57.0 |
| Nishi-kasai (西葛西) | 85.0 | 50.0 | 5.0 | 58.5 |
| Kasai (葛西) | 88.0 | 50.0 | 5.0 | 60.0 |
The 「スコア粒度(地震)」 box as displayed.
| Station | 「スコア粒度(地震)」 box as displayed |
|---|---|
| Nakano (中野) | 73(震度6強帯・1kmメッシュ・475年再現期間) |
| Ochiai (落合) | 73(震度6強帯・1kmメッシュ・475年再現期間) |
| Takadanobaba (高田馬場) | 70(震度6強帯・1kmメッシュ・475年再現期間) |
| Waseda (早稲田) | 70(震度6強帯・1kmメッシュ・475年再現期間) |
| Kagurazaka (神楽坂) | 70(震度6強帯・1kmメッシュ・475年再現期間) |
| Iidabashi (飯田橋) | 76(震度6強帯・1kmメッシュ・475年再現期間) |
| Kudanshita (九段下) | 76(震度6強帯・1kmメッシュ・475年再現期間) |
| Takebashi (竹橋) | 76(震度6強帯・1kmメッシュ・475年再現期間) |
| Otemachi (大手町) | 73(震度6強帯・1kmメッシュ・475年再現期間) |
| Nihombashi (日本橋) | 73(震度6強帯・1kmメッシュ・475年再現期間) |
| Kayabacho (茅場町) | 73(震度6強帯・1kmメッシュ・475年再現期間) |
| Monzen-nakacho (門前仲町) | 79(震度6強帯・1kmメッシュ・475年再現期間) |
| Kiba (木場) | 79(震度6強帯・1kmメッシュ・475年再現期間) |
| Toyocho (東陽町) | 82(震度6強帯・1kmメッシュ・475年再現期間) |
| Minami-sunamachi (南砂町) | 82(震度6強帯・1kmメッシュ・475年再現期間) |
| Nishi-kasai (西葛西) | 85(震度7帯・1kmメッシュ・475年再現期間) |
| Kasai (葛西) | 88(震度7帯・1kmメッシュ・475年再現期間) |
The line displayed under the score in the same box appeared in 1 form(s).
| Line as displayed | Stations |
|---|---|
| J-SHIS Y2024/MAX/TTL_MTTL (jshis-api-y2024-sampling1km) — メッシュ単位のハザード参照値であり、同一メッシュ内の住所は 同一スコアになります。 | 17 |
Reading the results
- Seismic: from 70.0 (Takadanobaba, Waseda, Kagurazaka) to 88.0 (Kasai), in 7 distinct values. The 6 stations from Monzen-nakacho eastward are all at 79.0 or above; the 11 stations west of it are all at 76.0 or below.
- Intensity class as displayed: the 「スコア粒度(地震)」 box showed 「震度6強帯」 at 15 stations; 「震度7帯」 at 2 stations (Nishi-kasai, Kasai).
- Flood: 4 distinct values (5.0, 25.0, 50.0, 70.0). 5.0, the value returned when no flood inundation polygon contains the point, appeared at 2 stations (Nakano, Kagurazaka); the largest value, 70.0, at Toyocho.
- Landslide: 5.0 at all 17 stations. That is the value returned when the point is in neither a warning area nor a special warning area.
- Overall: from 37.5 (Kagurazaka) to 63.0 (Toyocho).
- In the 「スコア粒度(地震)」 box, the score is followed by a source line and the remark 「メッシュ単位のハザード参照値であり、同一メッシュ内の住所は 同一スコアになります。」 (roughly: the value is a hazard reference per mesh, and addresses in the same mesh get the same score). The top of the page displayed 「Beta build 50e60ea」.
- These figures are a record for these 17 points. They do not generalise to the whole line or to any ward.
- The scores depend only on latitude and longitude, so for the same point they do not change with a building's structure or age.
Limits
- A station point is the centroid of the station geometry and can differ from where a user would place the station.
- Inclusion was decided with a ward boundary file whose accuracy we did not verify. For a station close to the boundary the result depends on that file (the administrative area data the product uses puts the same stations inside; this time only Urayasu, which is excluded, was within 500 m).
- The flood and landslide scores depend on whether the point lies inside an area polygon. The National Land Numerical Information page for the flood data says that the inundation extent and depth rank can differ from the flood assumptions published by river offices and prefectures and from the hazard maps distributed by municipalities.
- A flood or landslide score of 5.0 is the value returned when no polygon in the zone data the product has loaded contains the point entered. It does not indicate that the hazard is absent at that point.
- The 「スコア粒度(地震)」 box reads, for example at Nakano (中野), 「73(震度6強帯・1kmメッシュ・475年再現期間)」 (the text names a mesh size), and the footnote under it reads 「メッシュ単位のハザード参照値であり、同一メッシュ内の住所は 同一スコアになります。」 (in short: a reference value per mesh, the same score for addresses in the same mesh). The code at the commit above, however, uses the nearest stored cell within 1500 m of the point entered, and what is stored are 250 m cells extracted on a 0.01-degree grid. The mesh size shown on screen is a constant in the code. This note reports the screen as displayed and does not rely on the screen's statement about meshes.
- The Tokyo part of the landslide warning area data (2021 edition) carries this condition, quoted in the original: 「提供しているデータは、令和3年9月15日現在のもので、これ以降に区域変更等行っている場合があります。なお、実際に告示している区域については、公表している公示図書にてご確認ください。」 In short: the data is as of that date, areas may have changed since, and the officially notified areas must be checked in the published notices.
- The scores are the result of mappings the product defines. They are not a safety judgement on any building or site.
How to reproduce
- Sign in to DisasterShield and open
/try. - Enter a latitude and longitude from the table above and press 「スコア取得」.
- Read the 4 cards and the 「スコア粒度(地震)」 box.
- Go on to the next station. We left an interval between consecutive requests.
Data attribution
- Seismic: the figures shown are the result of DisasterShield loading and processing seismic hazard map data from J-SHIS, the Japan Seismic Hazard Information Station (National Research Institute for Earth Science and Disaster Resilience, https://www.j-shis.bosai.go.jp/). The source is J-SHIS.
- Flood and landslide: Source: MLIT National Land Numerical Information download site (flood inundation assumed area data, landslide disaster warning area data). The scores shown were created by DisasterShield by processing 「国土数値情報（洪水浸水想定区域データ、土砂災害警戒区域データ）」（国土交通省）.
- Station coordinates: Source: MLIT National Land Numerical Information download site (railway data). Created by processing 「国土数値情報（鉄道データ）」（国土交通省）; the centroid calculation and rounding are by DXA Labs.
- Administrative areas: Source: MLIT National Land Numerical Information download site (administrative area data). Created by processing 「国土数値情報（行政区域データ）」（国土交通省）; used to confirm that the stations are inside the product's coverage area.
- Ward boundaries: the Tokyo ward boundary file distributed by dataofjapan/land was used only to decide which stations to include. Its original source is Global Map Japan (Geospatial Information Authority of Japan).
- The scores are the result of DisasterShield processing the data above. They were not created or guaranteed by the data providers.
- Where each DXA Labs product gets its data is summarised in Data sources and measurements (Japanese); see also the DisasterShield documentation.