EQK · Physics
Earthquake
GEM PGA × Vs30 site amplification · v1.1.1 · 2026-07
San Francisco Bay to Salinas — high-PGA corridor along the San Andreas
Ground-shaking exposure from the GEM global 475-year seismic hazard model, refined for local soil amplification.
What ships
Surfaces — 0–1 susceptibility derived from the 475-year GEM PGA modulated by Vs30 amplification. Full-resolution (GSHHG-f) coastline: barrier islands now scored.
Every release: 0–1 score · 5-class band · per-pixel uncertainty · input-coverage mask · STAC item · methodology doc.
Inputs
GEM 2023 seismic hazard, USGS Vs30, soil-class amplification factors
Version history
What changed between releases — the same notes that ship with the data. Newest first.
v1.1.1
2026-07
current
- Full-resolution coastline (GSHHG-f). All four layers are re-clipped against the canonical GSHHG-f shoreline (~100 m native), so barrier islands and narrow coastal strips that previously read as NoData now carry a score. Any query over real land returns a result.
- Model unchanged. Susceptibility, classification, uncertainty, and coverage values are identical to v1.1 (differences are coastline-only); this vintage is a land-mask refresh, not a model revision.
- Product footprint is 84°N–60°S; Antarctica excluded by standard.
v1.1
2026-04
- Compact uint16 encoding. The surfaces were re-encoded from float32 to compact integer COGs with a documented scale (physical = raw × scale, nodata 65535) — smaller and self-describing, with no loss of precision at the delivered resolution. Method and values are unchanged from v1.0.
v1.0
2026-04
- Initial release. Susceptibility derived from the GEM 2023 global seismic-hazard model's 475-year peak ground acceleration (PGA), amplified for local site response via USGS Vs30 (with a Wald & Allen slope proxy where the USGS hybrid grid is unavailable), then ranked to a 0–1 percentile scale. A companion five-class map follows FEMA-style seismic zones (Negligible → Very High, keyed to 475-yr PGA in g), alongside per-pixel uncertainty and coverage.
- PGA = 0 is a real value, not a gap. Areas with no measurable seismic hazard read as the lowest class rather than nodata, so any query over land returns a result.
Other hazards
LandslideAvalancheWildfireWindstormExtreme heatExtreme coldFrost / freezeLightningSoil erosionHurricaneDrought