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J-SHIS EARTHQUAKE SOURCE MODEL

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

中央構造線断層帯（讃岐山脈南縁東部区間）

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

Reference model · not a forecast
Modelled magnitudeMw 7.1

The range of earthquake sizes represented by the whole model.

Chance within 30 years0.75%

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

Chance within 50 years1.43%

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 7.1. 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 0.75%, 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 7.1

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 years0.75%Within 50 years1.43%

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
900 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
520 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. Tokushima
  2. Naruto City
  3. Waki Mima Anabuki, Mima City
  4. Itano Town
  5. Handa Sadamitsu, Tsurugi Town
  6. Takamatsu City
  7. Sanuki City
  8. Higashikagawa City
  9. Shodoshima Town
  10. Miki Town
  11. Minamiawaji City
  12. Komatsushima City
Show 33 more places
  1. Anan City
  2. Yoshinogawa City
  3. Awa City
  4. Ishii Town
  5. Kamiita Town
  6. Tokushima City
  7. Kitajima Town
  8. Aizumi Town
  9. Higashimiyoshi Town
  10. Kagawa
  11. Sakaide City
  12. Matsushige Town
  13. Utazu Town
  14. Sumoto City
  15. Ayagawa Town
  16. Tonosho Town
  17. Okayama Minami Ward
  18. Tamano City
  19. Miyoshi City
  20. Katsuura Town
  21. Sanagochi Village
  22. Kamiyama Town
  23. Naoshima Town
  24. Kurashiki City
  25. Marugame City
  26. Tadotsu Town
  27. Zentsuji City
  28. Kanonji City
  29. Mitoyo City
  30. Manno Town
  31. Okayama
  32. Awaji City
  33. Hyogo

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
F020105
The identifier used for this model inside J-SHIS.
Estimation method code
BSI
An abbreviation for the statistical process used to calculate probability. It is not a danger grade.
Source elements
2
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
54–56 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
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
21
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 →