UCERF2

Of the hundreds of seismogenic (earthquake causing) geologic faults in California,[1] UCERF classifies only six faults as Type A sources, meaning there is sufficient information to both estimate and model the probability of a Magnitude (M) 6.7 or greater earthquake within 30 years.

[3] Faults which are known to be slipping (and therefore seismogenic) but lack sufficient information to fully model how close they might be to rupture are classified as Type B.

About twenty of these faults (see Table B) are estimated to have a 5% or greater chance of an M ≥ 6.7 earthquake within 30 years.

[4] An additional six areas where strain is accumulating but where knowledge is insufficient to apportion slip onto specific faults are classified as Type C sources.

Northern California has an estimated 12% chance over the same 30 years of an M ≥ 8 megathrust earthquake on the Cascadia subduction zone.

[6] UCERF has also prepared "participation probability maps"[7] of the chance that any area will experience an earthquake above a certain magnitude from any source in the next 30 years (see figure).

However, the details of how this happens are not adequately known, so time-dependent methods estimate the periodicity and currently accumulated strain based on observed seismicity.

Approximately twenty geologic faults in California are of "Type B" status, where the probability of an earthquake of M ≥ 6.7 in the next 30 years is estimated to be greater than 5%, but the data is insufficient for stress-renewal modeling.

(Not to be confused with the USGS QFFDB class B category of faults of unknown or minor seismicity.)

30b S. Rosa 29b 29c 35b 35c 141a 141b 141c Death V. 49b 49c 49d Goldfield 60b Monterey 142b 142c 142d Trona 143b 128b 128c 131b S. Diego Notes for Table B.