Reports Index
Branch Averaged Report
View Branch Averaged Solution Report
This report shows many properties of the fault system solution, as well as the input rupture set. Properties are branch-averaged across the entire logic tree, but some plots do show the range of values across all solutions.
Individual Branch Choice Reports
View Individual Branch Choice Reports
This page contains links to reports for subset solutions with each branch choice on the logic tree fixed. For example, if you want to see how one deformation model affects the solution, you could click on a report for that specific deformation model.
Hazard Maps
This page contains hazard maps, combined across fault and gridded seismicity branches. This helps to show how each branch choice affects hazard for various metrics. A single GMPE (ASK 2014) with default (hard rock) site parameters is used.
Hazard Comparisons with NSHM18:
| Peak Ground Acceleration | 1s Spectral Acceleration |
|---|---|
| 2% POE in 50 years | 2% POE in 50 years |
| 10% POE in 50 years | 10% POE in 50 years |
These pages contain hazard comparisons with NSHM18. Changes are shown separately for the fault and gridded seismicity models, and then the full hazard change is shown. A single GMPE (ASK 2014) with default (hard rock) site parameters is used.
Hazard Curves at Sites
View Full Logic Tree (including gridded) Curves
This page contains hazard curves at sites of interest, calculated and plotted in distinct colors for each individual logic tree branch. Results from NSHM18 are also included (listed as "Comparison"), including the full epistemic distribution from UCERF3 for sites in California.
Access Preliminary Model
A branch-averaged fault system solution for this preliminary model is available for review purposes only. The file format is documented here on the OpenSHA website.
Simplified solution containing only essential information for hazard calculations and basic analysis: Download zip file
Full (~1 GB) solution containing extra data used for analysis (not fully documented): Download zip file
Changelog
This Model: 4/11/2023, NSHM23 Version 2
This model incorporates the following changes:
- Revised branch weights:
- Segmentation models: Classic=10%, High=30%, Middle=30%, Low=20%, None=10%
- Declustering algorithms: Gardner-Knopoff=40%, Nearset-Neighbor=40%, Reasenburg=20%
- Seismicity smoothing kernel: Adaptive=60%, Fixed=40%
- Updated gridded seismicity model from Andrea and Andy (new rates and updated PDFs)
- Hardcoded slip rate std dev of 10% now applied as a cap to original values; lower values are retained to improve fits on high slip rate faults.
- New segmentation branch-specific rupture length caps: Classic=500 km, High=600 km, Middle=700 km, Low=800 km, None=unlimited.
- Cedar Mountain fault (ID=1257) was previously not part of the “Cedar Mountain” special fault group, but is now. From Alex: “Cedar Mountain fault (ID = 1257) should be added to this Special Fault list if it's not too late. The whole fault didn't rupture, but some scarps were on this fault..so probably best to add it.”
- New module to categorize tectonic regimes for ruptures for use in nshmp-haz calculations.
- Minor sparse G-R algorithm tweak: don’t spread moment from an empty single-fault mag bin to any multifault mags.
- Minor fix to section MFD uncertainty adjustments when paleo data conflicts with slip rate and b-value. Previous implementation was lower than stated: was accidentally
0.5*(sigma_orig + sigma_implied), rather than justsigma_implied.
Prior Model: 1/17/2023, NSHM23 Version 1
This earlier model incorporated the following changes:
- Cheraw fault was removed (east of the -104 longitude boundary, now considered a CEUS fault as in NSHM18)
- Corrected rakes in the Shen-Bird model. Inversion solutions rates are kept from the prior (12/23) model (also removing Cheraw, which was isolated); only the rakes are changed, which are not used in the inversion. This affects hazard calculations and branch averaged solution files only.
Earlier Model: 12/23/2022
This earlier model incorporated the following changes:
- Clean re-run with updated deformation model weights
- Minor update to initial solution for Parkfield ruptures (all zeros elsewhere)
Earlier Model: 12/7/2022
This earlier model incorporated the following changes:
- Removed proxy rate constraints from paleoseismic average slip data following recommendation of geologic review (unrealistic uncertainties & potentially biased)
- Updated deformation model weights to reduce influence of outliers. Updated weights: Evans=0.02, Geologic=0.26, Pollitz=0.08, Shen-Bird=0.32, Zeng=0.32
Earlier Model: 11/10/2022
This earlier model incorporated the following changes:
- Updated dip on Wasatch SLC segments
- Now uses hardcoded 10% slip rate uncertainties rather than uncertainties from deformation model
- New gridded seismicity model & rates
- Corrected special fault IDs for Lost River
- Fixed Wasatch paleo site mapping (site now on East Bench, was on Foothills)
- Fixed Mystic Lake paleo site location (now on SJF)
- West Valley fault DDW modified to no longer cross Wasatch (lower depth now 5 km)
- 10% default MFD uncertainty
- Fixed bug in application of slip rate std dev floor (was applied as 1e-4 m, not 1e-4 mm)