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J-SHIS EARTHQUAKE SOURCE MODEL

Fukaya/Ayasegawa fault zone (Kounosu-Ina segment/Ina-Kawaguchi segment)

深谷断層・綾瀬川断層（鴻巣－伊奈区間と伊奈－川口区間が同時に活動）

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

Reference model · not a forecast
Modelled magnitudeMw 7

The range of earthquake sizes represented by the whole model.

Chance within 30 years—

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

Chance within 50 years—

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 7. Its source elements span depths of 5–20.32 km below the surface.

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 depthShallow5 kmMid-range12.7 kmDeep20.3 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 7

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 years—Within 50 years—

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.

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. Kamagaya City
  2. Inashiki City
  3. Namegawa Town
  4. Ranzan Town
  5. Chiba Hanamigawa Ward
  6. Chiba Inage Ward
  7. Chiba Mihama Ward
  8. Narita City
  9. Sakura City
  10. Shiroi City
  11. Shisui Town
  12. Fuchu City
Show 48 more places
  1. Chofu City
  2. Kunitachi City
  3. Komae City
  4. Inagi City
  5. Kawasaki Tama Ward
  6. Kawasaki Asao Ward
  7. Koga City
  8. Yuki City
  9. Shimotsuma City
  10. Joso City
  11. Ushiku City
  12. Tsukuba City
  13. Bando City
  14. Kawachi Town
  15. Yachiyo Town
  16. Sakai Town
  17. Tone Town
  18. Oyama City
  19. Nogi Town
  20. Fukaya City
  21. Shiraoka City
  22. Ogawa Town
  23. Tokigawa Town
  24. Yorii Town
  25. Ichikawa City
  26. Funabashi City
  27. Matsudo City
  28. Kashiwa City
  29. Sakae Town
  30. Minato City
  31. Shinjuku City
  32. Tachikawa City
  33. Musashino City
  34. Koganei City
  35. Kodaira City
  36. Higashimurayama City
  37. Kokubunji City
  38. Higashiyamato City
  39. Kiyose City
  40. Higashikurume City
  41. Musashimurayama City
  42. Nishitokyo City
  43. Ryugasaki City
  44. Toride City
  45. Goka Town
  46. Ashikaga City
  47. Sano City
  48. Ota 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
F01482B
The identifier used for this model inside J-SHIS.
Estimation method code
SIM
An abbreviation for the statistical process used to calculate probability. It is not a danger grade.
Source elements
2
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
5–20.32 km
The modelled depth range below the ground surface.
Element length
20 km
The length of individual source elements, not necessarily the total length of a fault zone.
Element width
20 km
The width of the inclined source elements below ground.
Dip angle
50 °
The element’s tilt from horizontal: 0° is horizontal and 90° is vertical.
Strike
130.2–140.6 °
The compass direction in which an element extends, measured clockwise from north.
Display grid cells
14
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 →