Hazard Comparison: The PDFs in this directory are collections of plots showing hazard analyses at a single site. Curves are available for 3 hazard metrics: (1) 2% in 50 year recurrence [2in50], (2) 10% in 50yr recurrence [10in50], and (3) risk-targeted ground motion [RTGM], and at 3 periods of interest: (1) peak ground acceleration [PGA], (2) [5Hz] spectral acceleration, and (3) [1Hz] spectral acceleration. Note that RTGMs are only computed for 5Hz and 1Hz spectral accelerations. The curves are presented as Annual Frequency of Exceedance vs. Ground Motion (g) and the 2% in 50 year and 10% in 50 year recurrence rates are marked for reference (grey lines) where appropriate.

For these comparisons, UCERF3 hazard (blue) was computed from a suite of 'characteristic' constrained logic-:x tree solutions (1440 branches total with the average of 10 inversion runs, or solutions, per branch). The range of UCERF2 hazard (red) was computed from the 148 branches of the time-independent UCERF2 logic-tree. As a point of reference, the plots also show the ground motion for the return period of interest from the CA NSHMP model (green). There are occasional, slight deviations between this value and the mean UCERF2 value due to known model implementation differences.

Tornado diagrams show the influence of different logic-tree branch choices on hazard. Note that the tornado plots are keyed to the median hazard curve for the return period of interest (or RTGM), which is generally different than the weighted mean hazard of all logic-tree curves; the tornado diagrams show the weighted mean value for reference.

Source Comparison: PDFs are also available that illustrate how hazard is split between fault and background, or gridded, seismicity sources in both UCERF2 & UCERF3 at different periods of interest. These files begin with [BgFlt] and are color coded the same as the hazard comparison plots.

Legend:

DARK BLUE: weighted mean of 1440 logic-tree branches. On the curve plot, vertical lines mark the weighted mean (solid) and minimum and maximum (dashed) ground motions values for the return period of interest (or RTGM).

LIGHT BLUE: polygon showing minimum and maximum hazard for the 1440 UCERF3 logic-tree branches.

RED: weighted mean (solid) and minimum and maximum (dashed) hazard for the 148 time-independent UCERF2 branches.

GREEN: NSHMP reference ground motion value for the return period of interest (or RTGM).

Tornado diagram labels:

Various logic-tree branch identifiers have been shortened or modified from their representation in the published UCERF3 logic-tree according to the mapping below.

Fault Models:
   FM 3.1 : FM3.1
   FM 3.2 : FM3.2

Deformation Models:
   GEOL : Geologic
   ABM : AveBlockModel
   NEOK : NeoKinema
   ZENG : Zeng

Scaling Relationships:
   SHAW 09m : Shaw09mod
   SHAW CSD : Shaw09mod w/ConstStressDrop
   ELL B : EllsworthB
   ELL B SQL : EllsworthB w/SqrtLength
   H&B 08 : HanksBakun08

Slip Along Rupture (Dsr):
   TAPERED : Tapered
   UNIFORM : Boxcar

Total M≥5 Event Rate:
   M5+ 6.5 : 6.5
   M5+ 7.9 : 7.9
   M5+ 9.6 : 9.6

Maximum Off-Fault Magnitude:
   Mmax=7.3 : 7.3
   Mmax=7.6 : 7.6
   Mmax=7.9 : 7.9

Off-Fault Spatial Seis PDF:
   U2 SEIS : UCERF2 Smoothed Seis
   U3 SEIS : UCERF3 Smoothed Seis