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J-SHIS EARTHQUAKE SOURCE MODEL

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

中央構造線断層帯（讃岐山脈南縁西部区間～石鎚山脈北縁区間が同時に活動）

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 years—

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

Chance within 50 years<0.01%

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 2–16 km below the surface. It considers 2 rupture patterns; this is not the number of expected earthquakes.

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 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 years—Within 50 years<0.01%

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. Aki City
  3. Geisei Village
  4. Susaki City
  5. Otoyo Town
  6. Okayama Naka Ward
  7. Ibara City
  8. Mugi Town
  9. Kami City
  10. Motoyama Town
  11. Tosa Town
  12. Okawa Village
Show 48 more places
  1. Ochi Town
  2. Hidaka Village
  3. Soja City
  4. Setouchi City
  5. Hayashima Town
  6. Osakikamijima Town
  7. Niihama City
  8. Ozu City
  9. Tosa City
  10. Niyodogawa Town
  11. Bizen City
  12. Akaiwa City
  13. Satosho Town
  14. Takehara City
  15. Naka Town
  16. Kaiyo Town
  17. Tobe Town
  18. Kochi City
  19. Nankoku City
  20. Konan City
  21. Sakawa Town
  22. Okayama Higashi Ward
  23. Okayama Minami Ward
  24. Tamano City
  25. Kasaoka City
  26. Yakage Town
  27. Fukuyama City
  28. Minami Town
  29. Higashimiyoshi Town
  30. Naoshima Town
  31. Kotohira Town
  32. Saijo City
  33. Iyo City
  34. Shikokuchuo City
  35. Toon City
  36. Kamijima Town
  37. Ino Town
  38. Asakuchi City
  39. Onomichi City
  40. Marugame City
  41. Zentsuji City
  42. Kanonji City
  43. Tonosho Town
  44. Utazu Town
  45. Tadotsu Town
  46. Manno Town
  47. Imabari City
  48. Kurashiki 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
F0201FG
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
2–16 km
The modelled depth range below the ground surface.
Element length
30–86 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
253.9–255.8 °
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
34
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 →