Long-term context
Fault & hazard research
Historical dataMapped active faults and long-run seismicity rates. This is the decades-to-centuries picture that building codes are built on — deliberately kept apart from the short-term forecast, because converting one into the other is a category error.
Region
Convergence of the Pacific and Philippine Sea plates beneath the Eurasian and North American plates. Among the densest seismic networks on Earth, so the catalogue is unusually complete.
Active faults and historical seismicity
Long-run earthquake rates
Extrapolated from the magnitude-frequency relation fitted to this region
This is not an official hazard product. It is Prakruti extrapolating a b-value of 1.26 fitted over about 16 years of catalogue. National seismic hazard maps use fault geometry, palaeoseismology, geodesy and ground-motion models that this does not touch, and they are what building codes should rest on.
Extrapolating a decade of data to a per-century M8 rate is a long reach. The figure is shown because the alternative — a blank — is less informative, not because it is precise.
Time since the last large earthquake
Elapsed time is not a countdown. The seismic gap hypothesis — that a segment quiet for longer is more overdue — has repeatedly failed when tested prospectively. Earthquakes are not periodic, and a fault that has been quiet for a century is not thereby more likely to rupture tomorrow.
These figures are also bounded by the catalogue, which begins around 2011-01-01. “None held” means Prakruti has no such event on file, not that none has occurred.
Mapped active faults in this region
662 traces intersect this region; the highest-slip-rate ones are listed
| Fault | Slip type (observed) | Net slip rate (inferred) | Reference |
|---|---|---|---|
| unnamed trace | Subduction_Thrust | (88.0,,) | — |
| unnamed trace | Subduction_Thrust | (51.0,,) | — |
| unnamed trace | Subduction_Thrust | (83.8,,) | — |
| unnamed trace | Subduction_Thrust | (52.0,,) | — |
| unnamed trace | Subduction_Thrust | (80.5,,) | — |
| unnamed trace | Subduction_Thrust | (52.8,,) | — |
| unnamed trace | Subduction_Thrust | (77.8,,) | — |
| Tobiyozaki | Normal | (1.0,,) | — |
| unnamed trace | Subduction_Thrust | (75.7,,) | — |
| unnamed trace | Subduction_Thrust | (73.9,,) | — |
| unnamed trace | Subduction_Thrust | (53.5,,) | — |
| unnamed trace | Subduction_Thrust | (72.4,,) | — |
| unnamed trace | Subduction_Thrust | (71.4,,) | — |
| unnamed trace | Subduction_Thrust | (54.3,,) | — |
| unnamed trace | Subduction_Thrust | (69.5,,) | — |
| unnamed trace | Subduction_Thrust | (66.5,,) | — |
| unnamed trace | Subduction_Thrust | (55.2,,) | — |
| unnamed trace | Subduction_Thrust | (63.1,,) | — |
| unnamed trace | Subduction_Thrust | (56.0,,) | — |
| unnamed trace | Subduction_Thrust | (60.2,,) | — |
| Onoma | Normal | (0.1,,) | — |
| unnamed trace | Subduction_Thrust | (58.0,,) | — |
| Kerizaki-Tanowaki | Sinistral | (0.1,,) | — |
| unnamed trace | Subduction_Thrust | (56.9,,) | — |
| unnamed trace | Subduction_Thrust | (55.7,,) | — |
| unnamed trace | Spreading_Ridge | (2.9,,) | — |
| unnamed trace | Subduction_Thrust | (55.2,,) | — |
| unnamed trace | Spreading_Ridge | (4.5,,) | — |
| Kimondaira | Normal | (1.0,,) | — |
| unnamed trace | Subduction_Thrust | (54.5,,) | — |
| unnamed trace | Subduction_Thrust | (57.9,,) | — |
| unnamed trace | Subduction_Thrust | (53.7,,) | — |
| Kagoshimawan-seien | Normal | (0.0,,) | — |
| Kagoshimawan-toen | Normal | (0.0,,) | — |
| Gotanda | Normal | (0.0,,) | — |
| unnamed trace | Subduction_Thrust | (52.6,,) | — |
| unnamed trace | Subduction_Thrust | (58.8,,) | — |
| Izumi | Dextral | None | — |
| Hitoyoshi | Normal | (0.3,,) | — |
| unnamed trace | Subduction_Thrust | (51.8,,) | — |
Traces are observations; rates are inferences. A mapped trace is where geologists have identified a fault at the surface. A slip rate is derived from offset landforms, dated deposits or geodesy, often with uncertainty of a factor of two or more, and it is frequently absent altogether. Prakruti labels the two differently everywhere rather than presenting them as one dataset.
Many damaging earthquakes occur on faults not on any map — blind thrusts with no surface expression, or structures never surveyed. A gap in this table is a gap in knowledge, not a safe area.
Source: Styron, R. and Pagani, M. (2020), The GEM Global Active Faults Database, Earthquake Spectra (CC BY-SA 4.0) · a periodic release, not a live feed
Largest earthquakes held for this region
- 2011 Great Tohoku Earthquake, JapanM9.12011-03-11 05:46:24 UTC
- 47 km E of ?arai, JapanM7.92011-03-11 06:15:40 UTC
- Bonin Islands, Japan regionM7.82015-05-30 11:23:02 UTC
- 272 km ESE of Kamaishi, JapanM7.72011-03-11 06:25:50 UTC
- 2025 Aomori Prefecture, Japan EarthquakeM7.62025-12-08 14:15:09 UTC
- 2024 Noto Peninsula, Japan EarthquakeM7.52024-01-01 07:10:09 UTC
- 102 km ENE of Miyako, JapanM7.42026-04-20 07:52:58 UTC
- 120 km SE of ?funato, JapanM7.32011-03-09 02:45:20 UTC
Rate-and-state friction research
Not implemented, and not faked. Rate-and-state friction describes how fault strength evolves with slip rate and contact age, and it is the physical basis for how a stress change alters earthquake timing. Running it usefully needs fault-specific friction parameters (a, b, characteristic slip distance), a stress-change model, and loading rates — none of which Prakruti holds for the faults above.
A simulation run on assumed parameters would produce confident-looking failure times that are entirely a function of the assumptions. That is worse than an empty section, so this one stays empty until real parameters are available. The fault geometry above is the first piece of what such a module would need.