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J-SHIS EARTHQUAKE SOURCE MODEL

Median Tectonic Line (MTL) fault zone (FROM Sanuki-sanmyaku-nanen eastern segment TO Sanuki-sanmyaku-nanen western segment)

中央構造線断層帯（讃岐山脈南縁東部区間～讃岐山脈南縁西部区間が同時に活動）

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

Reference model · not a forecast
Modelled magnitudeMw 7.5

The range of earthquake sizes represented by the whole model.

Chance within 30 years0.02%

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

Chance within 50 years0.05%

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 4–16 km below the surface. It considers 2 rupture patterns; this is not the number of expected earthquakes. Its 30-year long-term probability is 0.02%, 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 depthShallow4 kmMid-range10 kmDeep16 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 years0.02%Within 50 years0.05%

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. Okayama Kita Ward
  2. Soja City
  3. Tatsuno City
  4. Geisei Village
  5. Okayama Naka Ward
  6. Yakage Town
  7. Miyoshi City
  8. Mitoyo City
  9. Shikokuchuo City
  10. Ibara City
  11. Setouchi City
  12. Anan City
Show 48 more places
  1. Kanonji City
  2. Niihama City
  3. Okayama
  4. Kurashiki City
  5. Waki Mima Anabuki, Mima City
  6. Sanagochi Village
  7. Mugi Town
  8. Handa Sadamitsu, Tsurugi Town
  9. Higashimiyoshi Town
  10. Kagawa
  11. Takamatsu City
  12. Marugame City
  13. Zentsuji City
  14. Sanuki City
  15. Miki Town
  16. Ayagawa Town
  17. Tadotsu Town
  18. Manno Town
  19. Imabari City
  20. Saijo City
  21. Okayama Higashi Ward
  22. Naruto City
  23. Yoshinogawa City
  24. Awa City
  25. Sakaide City
  26. Higashikagawa City
  27. Utazu Town
  28. Kotohira Town
  29. Aki City
  30. Nankoku City
  31. Susaki City
  32. Konan City
  33. Motoyama Town
  34. Otoyo Town
  35. Okawa Village
  36. Minamiawaji City
  37. Okayama Minami Ward
  38. Akaiwa City
  39. Asakuchi City
  40. Hayashima Town
  41. Satosho Town
  42. Tokushima
  43. Tokushima City
  44. Komatsushima City
  45. Katsuura Town
  46. Naka Town
  47. Minami Town
  48. Kaiyo Town

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
F0201EF
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
4
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
4–16 km
The modelled depth range below the ground surface.
Element length
54–86 km
The length of individual source elements, not necessarily the total length of a fault zone.
Element width
12–18 km
The width of the inclined source elements below ground.
Dip angle
40–90 °
The element’s tilt from horizontal: 0° is horizontal and 90° is vertical.
Strike
255.8–257.3 °
The compass direction in which an element extends, measured clockwise from north.
Rupture patterns
2
Alternative rupture arrangements or sequences considered by the model.
Display grid cells
47
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 →