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J-SHIS EARTHQUAKE SOURCE MODEL

Tachikawa fault zone

立川断層帯

What this earthquake source model represents and how to read its data.

Reference model · not a forecast
Modelled magnitudeMw 6.8

The range of earthquake sizes represented by the whole model.

Chance within 30 years2.21%

The long-term chance that an earthquake represented by this model occurs within that period.

Chance within 50 years3.66%

The long-term chance that an earthquake represented by this model occurs within that period.

This model in plain language

J-SHIS classifies this as a major active-fault model. It represents the underground area that may rupture along the fault, not one predicted earthquake. The model covers an overall magnitude of Mw 6.8. Its source elements span depths of 2–19.73 km below the surface. Its 30-year long-term probability is 2.21%, not a prediction of a date.

Japan terrain and the source model in 3D

Use the terrain map and city labels to locate the approximate source area, then switch below ground to inspect its generalised extent and depth. It does not reproduce the original source elements or show future epicentres or rupture progression.

Ctrl-drag to tilt · city names remain visible on the map

Colour shows generalised depthShallow2 kmMid-range10.9 kmDeep19.7 km

The 3D terrain gives geographic and city context. The coloured surfaces are coarse regular display cells projected from the underground source area—not the original J-SHIS geometry. They do not show future epicentres or shaking intensity.

How to read the model data

Modelled magnitudeMw 6.8

Magnitude describes the overall size of the modelled earthquake, not the Shindo felt in a particular place. The same magnitude can produce different shaking depending on distance, depth and ground conditions. A range shows both model limits.

Occurrence probability
Within 30 years2.21%Within 50 years3.66%

Probabilities are long-term values in the Y2020 model. They do not predict an earthquake on a particular day, in a particular year or at one exact location. Some models do not provide a value.

Average recurrence interval
10,000 years
A long-term average derived from the activity assessment. It is not a timetable or a countdown to the next event.
Time since latest modelled activity
20,000 years
How much time the model treats as having passed since the latest activity. It is uncertain and is not the time remaining until another earthquake.

Do not subtract the elapsed time from the average interval to calculate a countdown to the next earthquake.

Places where J-SHIS considers this model

In J-SHIS calculations, this model is among the leading earthquake sources for these places. It does not mean the earthquake will start inside their boundaries or that every place would shake in the same way.

  1. Ome City
  2. Tokorozawa City
  3. Hanno City
  4. Sayama City
  5. Iruma City
  6. Asaka City
  7. Wako City
  8. Niiza City
  9. Fujimi City
  10. Hidaka City
  11. Miyoshi Town
  12. Moroyama Town
Show 48 more places
  1. Tokyo
  2. Shinagawa City
  3. Meguro City
  4. Setagaya City
  5. Shibuya City
  6. Nakano City
  7. Suginami City
  8. Nerima City
  9. Hachioji City
  10. Tachikawa City
  11. Musashino City
  12. Mitaka City
  13. Fuchu City
  14. Akishima City
  15. Chofu City
  16. Machida City
  17. Koganei City
  18. Kodaira City
  19. Hino City
  20. Higashimurayama City
  21. Kokubunji City
  22. Kunitachi City
  23. Fussa City
  24. Komae City
  25. Higashiyamato City
  26. Kiyose City
  27. Higashikurume City
  28. Musashimurayama City
  29. Tama City
  30. Inagi City
  31. Hamura City
  32. Akiruno City
  33. Nishitokyo City
  34. Mizuho Town
  35. Hinode Town
  36. Okutama Town
  37. Yokohama Aoba Ward
  38. Yokohama Tsuzuki Ward
  39. Kawasaki Nakahara Ward
  40. Kawasaki Takatsu Ward
  41. Kawasaki Tama Ward
  42. Kawasaki Miyamae Ward
  43. Kawasaki Asao Ward
  44. Sagamihara Chuo Ward
  45. Saitama Nishi Ward
  46. Saitama Sakura Ward
  47. Saitama Minami Ward
  48. Kawaguchi City

Technical model data

J-SHIS identifiers and calculation parameters. You do not need them for an everyday reading of this page.

Model version
Y2020
The edition of J-SHIS data used on this page.
Probability case
MAX
MAX is the J-SHIS calculation case used on this page. It does not mean a certain ‘worst case’ event.
J-SHIS code
F015021
The identifier used for this model inside J-SHIS.
Estimation method code
BPT
An abbreviation for the statistical process used to calculate probability. It is not a danger grade.
Source elements
1
Source elements are the pieces J-SHIS uses to build the source shape. A larger count means a more detailed or complex model; it is not a hazard score, a fault count or the number of expected earthquakes.
Depth
2–19.73 km
The modelled depth range below the ground surface.
Element length
34 km
The length of individual source elements, not necessarily the total length of a fault zone.
Element width
18 km
The width of the inclined source elements below ground.
Dip angle
80 °
The element’s tilt from horizontal: 0° is horizontal and 90° is vertical.
Strike
315 °
The compass direction in which an element extends, measured clockwise from north.
Display grid cells
8
Regular aggregated grid cells used to depict the source area. This is not the number of source records or original shapes.

Source and limitations

Source: J-SHIS, operated by Japan’s National Research Institute for Earth Science and Disaster Resilience (NIED). JISHINDESU organises the Y2020 maximum-case data for presentation. This page is not an earthquake prediction, building-safety assessment or evacuation notice. Use current JMA and local-authority information for safety decisions.

In accordance with the J-SHIS terms, we publish only model-level summaries and coarse display geometry that cannot reproduce the original vertex sequences. This is not a redistributed copy of the source dataset.

Data retrieved: 05/09/2026

Open the source data in J-SHIS ↗J-SHIS terms of use ↗Explore local earthquake history →