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J-SHIS EARTHQUAKE SOURCE MODEL

Nagaoka-heiya-seien fault zone

長岡平野西縁断層帯

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

Reference model · not a forecast
Modelled magnitudeMw 7.5

The range of earthquake sizes represented by the whole model.

Chance within 30 years2.42%

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

Chance within 50 years4.28%

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 7.5. Its source elements span depths of 6–25.66 km below the surface. Its 30-year long-term probability is 2.42%, 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 depthShallow6 kmMid-range15.8 kmDeep25.7 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 7.5

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 years2.42%Within 50 years4.28%

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
1,200 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
820 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. Tadami Town
  2. Niigata
  3. Niigata Kita Ward
  4. Niigata Higashi Ward
  5. Niigata Chuo Ward
  6. Niigata Konan Ward
  7. Niigata Akiha Ward
  8. Niigata Minami Ward
  9. Niigata Nishi Ward
  10. Niigata Nishikan Ward
  11. Nagaoka City
  12. Sanjo City
Show 32 more places
  1. Kashiwazaki City
  2. Ojiya City
  3. Kamo City
  4. Tokamachi City
  5. Mitsuke City
  6. Tsubame City
  7. Agano City
  8. Sado City
  9. Uonuma City
  10. Minamiuonuma City
  11. Yahiko Village
  12. Tagami Town
  13. Izumozaki Town
  14. Kariwa Village
  15. Gosen City
  16. Joetsu City
  17. Seiro Town
  18. Tsunan Town
  19. Awashimaura Village
  20. Aga Town
  21. Sekikawa Village
  22. Sakae Village
  23. Shibata City
  24. Murakami City
  25. Tainai City
  26. Kijimadaira Village
  27. Itoigawa City
  28. Myoko City
  29. Nakano City
  30. Iiyama City
  31. Fukushima
  32. Nagano

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
F002701
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
6–25.66 km
The modelled depth range below the ground surface.
Element length
84 km
The length of individual source elements, not necessarily the total length of a fault zone.
Element width
24 km
The width of the inclined source elements below ground.
Dip angle
55 °
The element’s tilt from horizontal: 0° is horizontal and 90° is vertical.
Strike
185 °
The compass direction in which an element extends, measured clockwise from north.
Display grid cells
22
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 →