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J-SHIS EARTHQUAKE SOURCE MODEL

Itoigawa-Shizuoka-kozosen fault zone (Northern segment/Central northern segment/Central southern segment)

糸魚川－静岡構造線断層帯（北部と中北部と中南部が同時に活動）

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

Reference model · not a forecast
Modelled magnitudeMw 7.4

The range of earthquake sizes represented by the whole model.

Chance within 30 years1.38%

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

Chance within 50 years2.27%

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 7.4. Its source elements span depths of 2–16.12 km below the surface. Its 30-year long-term probability is 1.38%, 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-range9.1 kmDeep16.1 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 7.4

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 years1.38%Within 50 years2.27%

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. Nagano, Nagano City
  2. Ueda City
  3. Tomi City
  4. Koumi Town
  5. Tateshina Town
  6. Aoki Village
  7. Nagawa Town
  8. Iizuna Town
  9. Itoigawa City
  10. Myoko City
  11. Nirasaki City
  12. Nagano
Show 48 more places
  1. Komoro City
  2. Ina, Ina City
  3. Nakano City
  4. Iiyama City
  5. Kitaaiki Village
  6. Minowa Town
  7. Sakaki Town
  8. Obuse Town
  9. Yamanouchi Town
  10. Hokuto City
  11. Matsumoto, Matsumoto City
  12. Suzaka City
  13. Omachi City
  14. Saku City
  15. Chikuma City
  16. Sakuho Town
  17. Tatsuno Town
  18. Minamiminowa Village
  19. Omi Village
  20. Yamagata Village
  21. Chikuhoku Village
  22. Hakuba Village
  23. Otari Village
  24. Shinano Town
  25. Ogawa Village
  26. Joetsu City
  27. Uozu City
  28. Namerikawa City
  29. Kurobe City
  30. Kamiichi Town
  31. Nyuzen Town
  32. Minamialps City
  33. Chuo City
  34. Okaya City
  35. Azumino City
  36. Kawakami Village
  37. Minamiaiki Village
  38. Miyota Town
  39. Shimosuwa Town
  40. Ikusaka Village
  41. Asahi Village
  42. Matsukawa Village
  43. Funahashi Village
  44. Kai City
  45. Chino City
  46. Shiojiri, Shiojiri City
  47. Fujimi Town
  48. Hara Village

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
F01622D
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
12
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
2–16.12 km
The modelled depth range below the ground surface.
Element length
5.7–33.9 km
The length of individual source elements, not necessarily the total length of a fault zone.
Element width
4–14 km
The width of the inclined source elements below ground.
Dip angle
30–70 °
The element’s tilt from horizontal: 0° is horizontal and 90° is vertical.
Strike
2–343.7 °
The compass direction in which an element extends, measured clockwise from north.
Display grid cells
23
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 →