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This translation was generated by AI and may contain wording that differs from the facts. Please check the Japanese original or official sources for anything important. Japanese original
🎛 Set it up
Click the map to move the epicentre there. Hover over the map to see the estimated shaking at any point.
📳 Results
🗾 Compare with real events
- Nankai Trough megaquake (government scenario, M9.1): The Japanese government's scenario puts shindo 7 in parts of the coast from Shizuoka to Miyazaki and shindo 6 Lower or more over a wide area.
- Tokyo inland earthquake (scenario under southern central Tokyo, M7.3): The government scenario puts shindo 6 Upper across much of Tokyo's 23 wards and 7 in places. Set the ground to 'soft' to get closer to it.
- Great East Japan Earthquake (2011, M9.0): The strongest observed shaking was shindo 7 (Kurihara, Miyagi). Sendai, Fukushima and Mito saw 6 Lower to 6 Upper, and Tokyo 5 Upper.
- Great Hanshin (Kobe) Earthquake (1995, M7.3): The strongest shaking was shindo 7 in a belt through Kobe and nearby. Damage concentrated right above the fault and on soft ground.
- Kumamoto Earthquake (2016, main shock M7.3): Shindo 7 was recorded twice, in the foreshock and main shock, in Mashiki and nearby towns in Kumamoto.
- Noto Peninsula Earthquake (2024, M7.6): The strongest shaking was shindo 7 (Shika, Ishikawa), with 6 Upper in Wajima, Suzu and other towns.
⚙️ How it works
Shaking strength (peak ground velocity) is calculated with the attenuation relation that Si and Midorikawa (1999) derived from Japanese earthquake records. It depends on magnitude, depth, quake type and distance from the fault.
Bigger earthquakes rupture longer and wider faults, so distance is measured from a rectangular fault plane rather than a single point. For the past and scenario quakes, the fault's approximate position, direction and dip are built in.
The velocity is multiplied by a ground amplification factor (firm, average or soft) and converted to the Japan Meteorological Agency's instrumental shindo with the formula of Midorikawa et al. (1999).
S-wave (strong shaking) arrival time is the distance from the focus divided by 3.5 km/s. Results can differ from real observations by about one level.
📚 Sources and further reading
- Si, H., Midorikawa, S. (1999) New attenuation relationships for peak ground acceleration and velocity considering effects of fault type and site condition. Journal of Structural and Construction Engineering (AIJ) 523.
- Midorikawa, S., Fujimoto, K., Muramatsu, I. (1999) Correlation of new J.M.A. instrumental seismic intensity with former J.M.A. seismic intensity and ground motion parameters. Journal of Social Safety Science 1.
- Japan Meteorological Agency – seismic intensity (shindo)
- Cabinet Office of Japan – Nankai Trough earthquake
- Cabinet Office of Japan – Tokyo inland earthquake
- NIED J-SHIS Japan Seismic Hazard Information Station
- Map data © OpenStreetMap contributors
This simulator gives rough estimates using published research formulas. Real damage depends heavily on terrain, buildings and weather. For disaster planning or evacuation decisions, use official estimates and information from your government and local authorities.
Try the other simulator: Asteroid impact simulator → Japan disaster guide
Frequently asked questions
What is the difference between shindo and magnitude?
Magnitude is the size of the earthquake itself (the energy released), one number per quake. Shindo is how strongly the ground shakes at a particular place, so the same quake gives lower shindo farther away and on firmer ground. Japan's scale has 10 levels from 0 to 7, with 5 and 6 split into Lower and Upper.
How strong would a Nankai Trough megaquake be?
In the government's worst-case (M9-class) scenario, parts of the coast from Shizuoka to Miyazaki would see shindo 7 and a wide surrounding area 6 Lower to 6 Upper. Local details are on each municipality's hazard map.
How many seconds before strong shaking arrives?
The farther you are from the focus, the longer before strong shaking (S-waves) arrives — roughly 30 seconds at 100 km. Close to the focus, an Earthquake Early Warning may not arrive in time. If you feel shaking, protect yourself first.
