Reading the earthquake probability, with medians by prefecture
The J-SHIS probabilistic seismic hazard map, published by Japan's National Research Institute for Earth Science and Disaster Resilience (NIED), estimates for any point in the country the probability of shaking of Shindo 6-lower or above within the next 30 years. Settle Map reads that value at each town hall and uses it as its earthquake metric. This table lists the 47 prefectures ordered by the median of their municipalities.
Across 1,892 municipalities the nationwide median is 19.3%. The lowest prefectural median is Shimane (2.1%) and the highest is Tokushima (73.8%); 4 prefectures have a median of 70.0% or more and 9 sit below 5.0%. Individual municipalities spread even wider, from Shimane / 知夫村 (0.0%) up to Ibaraki / 河内町 (96.5%).
How to read this table
Prefectures along the Nankai Trough — Shizuoka, Aichi, Mie, Wakayama, Tokushima and Kochi — cluster near 70.0%. That does not mean strong shaking happens in seven of every ten 30-year periods in a plain sense; it is the combined likelihood of every earthquake the model considers, expressed as one probability.
On the Sea of Japan side and in northern Kyushu, medians of a few per cent are common. A low probability is not the same as no shaking: the 2016 Kumamoto and 2024 Noto Peninsula earthquakes both struck areas that were far from the top of this list. The metric measures how unlikely strong shaking is, not that it cannot happen.
Within a single prefecture the range is wide. Comparing the lowest and the highest municipality in a row often shows a difference of an order of magnitude. Follow a prefecture name to see all of its municipalities ranked from the lowest probability.
What the numbers do not tell you
The value is read from a single 250 m mesh cell at the town hall, not averaged over the municipal area. In large municipalities, districts far from the town hall can differ.
The probability includes amplification by shallow ground, but says nothing about how buildings are built, about liquefaction, tsunami or slope failure. At the same probability, damage still depends on the structure and the ground beneath it.
J-SHIS is revised roughly every year and values move when the underlying scenarios are reviewed. The sources page records which edition was used and when it was retrieved; check the original before acting on it.
See the earthquake probability on the map