1. NGA Project Review and Status Norm Abrahamson NGA Workshop #5 March, 2004

2. Developer Scope Ground Motion Model (median, standard dev) –Ground Motion Parameters: Horizontal components (Ave Horiz, FN, and FP) PGA, PGV, PGD Pseudo spectral acc at 5% damping: 0-10 sec –Applicable Magnitude Range: 5.0 - 8.5 (SS) 5.0 - 8.0 (RV) –Applicable Distance Range: 0 - 200 km –Fault Types Strike-slip, Reverse, Normal –Site Classification Scheme Developers select their preferred classification scheme Need not include soft-soil

3. Developer Scope (cont) Ground Motion Data Set –Common data set provided to developers –Each developer selects applicable subset of data Justify the exclusion of earthquakes and recording sites Document any modification of independent parameters from PEER recommended values Ground motion values are not modified (e.g. common set used by all developers), but developers select applicable period range of each recording –Final selected data to be listed in report

4. Developer Scope (cont) Evaluate new predictive parameters –Directivity parameters –Hanging wall / foot wall –Static stress-drop –Asperity depth –Depth to bedrock (or Vs) –Basin parameters Each developer decides if new predictive parameter is to be included in their model –Justify the selection or rejection of each parameter evaluated

5. Developer Scope (cont) Spectral Periods –112 periods provide (from 0.01 to 10 sec –Minimum set of 20 periods required for model: 0.02, 0.03, 0.05, 0.075, 0.10, 0.15, 0.20, 0.25, 0.30, 0.40, 0.50, 0.75, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0, 7.5, 10

6. Developer Scope (cont) Magnitude definition –All developers use moment magnitude Distance definition –Developers select appropriate distance metric Site classification –Developers select site classification Clear definition of site classes –Provide a translation scheme to NERHP categories

7. Tasks to Support NGA Developers 1.Empirical database development 2.1-D rock simulations 3.Evaluation of source-path predictor variables 4.Evaluation of site classification and site effects 5.Site response simulations 6.Statistical approaches 7.3-D basin response simulations 8.Compilation of seismic network ground motion data for M5 at large distances

8. Working Groups 1.Data Processing 2.Ground Motion Database 3.Validation of 1-D Rock Motion Simul 4.Source/Path Effects 5.Site Classification & Site Effects 6.Statistical Modeling of Data

9. NGA Tasks and Associated WGs TaskWorking Group 1. Database developmentWG#1 data proc WG#2 Database WG#4 Source/Path WG#5 Site Classification 2. 1-D rock SimulationWG#3 Valid of 1-D simulations WG#4 Source/Path 3. Evaluation source/Path EffectsWG#4 Source/Path 4. Evaluation of site classificationWG#5 Site Classification 5. Site Response SimulationsWG#5 Site Classification 6. Statistical ApproachesWG#6 Statistical Modeling 7. 3-D basin SimulationsWG#4 Source/Path WG#5 Site Classification 8. Network DataWG#4 Source/Path

10. Task 1 Empirical Database Development Metadata –Version 1 released in November Source and path parameters review by Somerville (complete) Site parameters review by Wells (not complete) –Modifications Incorporate review comments Next version due April 23 Includes rotations to FN and FP

11. Task 1 (cont) Empirical Database Development Ground Motion Values –Evaluation of adequacy of processing in progress (comparison of PEER Sa values with CSMIP and USGS Sa values) – WG #1 Meeting held March 17 Summary to be given by Abrahamson –Evaluation of treatment of permanent displacements (fling step) – WG#1 Update to be given by Graves

12. Task 2 1-D Rock Motion Simulation Validations –URS, Silva, Zeng (not complete) –Update to be presented Simulations –Strike-slip scenarios URS complete, Zeng nearly complete (missing SJ) Silva results preliminary (to be updated) –Reverse-slip scenarios URS complete, Zeng (7 events complete) Silva results due March 31

13. Task 3 Evaluation of Source-Path Predictor Variables Review of Metadata by WG#4 –Source and travel path parameters Review completed (Somerville) WG#4 –1-D rock simulations Updated scaling results to be shown (Abrahamson) Directivity model using Isochrons –Spudich working on model refinements –3-D basin simulations(mtg held Mar 5) Scale factors to be discussed by Steve Day

14. Task 4 Evaluation of Site Classification and Site Effects Review of Metadata (WG#5) –Recording site classification –Structure (building) classification –Review by Wells to be completed April 2 Review alternative site classification schemes and functional forms for site effects (WG#5) –Evaluate site response simulations and empirical data Develop method for translations among different site classification schemes (WG#5) –Not started

15. Task 5 Site Response Simulations Simulation method –RASCALS with soil randomization Simulations –Previous PEER-LL and NEHRP studies (Silva) –Augment previous simulations Identify additional cases needed (April 5) Results in May Sensitivity analysis –Comparisons with RASCAL, SHAKE, and Non-linear models Completed. To be shown by Sun

16. Task 6 Statistical Approaches Issues (WG#6) –Review of alternative methods Weights, two-step, random effects, … –Spatial correlation of ground motion –Correlation of spectra at different frequencies –Standard deviation Dependence on magnitude, distance, and soil type –Incorporating measurement errors in predictor variables –Missing predictor variables –Censored data (non-triggered stations) –Combining empirical and simulated data in regression analyses (NGA-H) WG#6 held initial meeting –Scope of work identified WG#6 recommendations in May

17. Task 7 3-D Bain Simulations Program verification completed Simulations completed Evaluation of results –Will be presented Thursday

18. Task 8 Network Data Evaluation Evaluation of attenuation at large distances using network data –Complete –Presented by Boatwright in WS#4

19. Revised Schedule March 24-25Workshop #5 April 20Draft summary of supporting task reports May 6-7Developer interaction meeting June 24-25NGA workshop #6, –Developers present preliminary model –Developers explain July 12Draft report due –Describe approach and preliminary model –For circulation to other developers July 19-26? Developer interaction meeting Sep 17Final models due Sep 30Final report due Oct 14-15Final workshop –Compare models (other developer’s models and past models) –Examine impacts on hazard

20. NGA Reports Data Report –Documentation of data set in flat file Resource Report –Documentation of results from supporting tasks and working groups NGA Ground Motion Report –Documentation of the developers models Summary, Overview, and Impacts

21. Data Report Metadata –Documentation of magnitudes, source geometries, site conditions, distances, directivity parameters, HW/FW, etc Ground motion processing –Causal vs acausal –Filter corners –Fling step removal QA Efforts – Reviews of metadata and response spectra

22. Resource Report Working Group Activities Scaling factors based on 1-D rock simulations Basin scaling factors based on 3-D simulations Directivity functional form based on Isochron Site response amplification factors Attenuation rates from network data Statistical approaches

23. NGA Ground Motion Model Report Synthesis of developer’s models Model report from each developer Fling step model –(for adding fling back into ground motion)

24. Summary and Impacts General report summarizing NGA project Focus on impacts of new models –How do the new models effects the design ground motions for future projects?