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J-SHIS EARTHQUAKE SOURCE MODEL

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

中央構造線断層帯（讃岐山脈南縁西部区間～伊予灘区間が同時に活動）

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

Reference model · not a forecast
Modelled magnitudeMw 7.7

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 7.7. 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 7.7

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. Kihoku Town
  2. Ainan Town
  3. Yusuhara Town
  4. Kumano Town
  5. Tabuse Town
  6. Uwajima City
  7. Yawatahama City
  8. Seiyo City
  9. Uchiko Town
  10. Ikata Town
  11. Saiki City
  12. Tsukumi City
Show 48 more places
  1. Kudamatsu City
  2. Hirao Town
  3. Nakatosa Town
  4. Usuki City
  5. Bungo Ohno City
  6. Hikari City
  7. Ozu City
  8. Himeshima Village
  9. Hiroshima City Naka Ward
  10. Hiroshima City Minami Ward
  11. Hiroshima City Aki Ward
  12. Kaita Town
  13. Kaminoseki Town
  14. Kitsuki City
  15. Yufu City
  16. Kunisaki City
  17. Fuchu Town
  18. Suo Oshima Town
  19. Tobe Town
  20. Oita City
  21. Beppu City
  22. Hiji Town
  23. Hiroshima City Saeki Ward
  24. Yanai City
  25. Iyo City
  26. Susaki City
  27. Buzen City
  28. Koge Town
  29. Toon City
  30. Niyodogawa Town
  31. Ochi Town
  32. Hidaka Village
  33. Yoshitomi Town
  34. Bungotakada City
  35. Kokonoe Town
  36. Shunan City
  37. Kumakogen Town
  38. Tosa City
  39. Sakawa Town
  40. Usa City
  41. Hiroshima City Nishi Ward
  42. Otake City
  43. Tosa Town
  44. Ino Town
  45. Hatsukaichi City
  46. Etajima City
  47. Iwakuni City
  48. Kamijima 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
F0201FI
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
6
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
42–92 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
240.7–255.8 °
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
70
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 →