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Status and recent updates of the Community Velocity Models (CVM and CVM-H) A. Plesch

Status and recent updates of the Community Velocity Models (CVM and CVM-H) A. Plesch. CVM @ 2000m. SCEC provides two alternative velocity models: CVM and CVM-H. 1) Define basic structure of these models 2) Highlight their similarities and differences 3) Define viable paths for improvement.

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Status and recent updates of the Community Velocity Models (CVM and CVM-H) A. Plesch

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  1. Status and recent updates of the Community Velocity Models (CVM and CVM-H) A. Plesch CVM @ 2000m SCEC provides two alternative velocity models: CVM and CVM-H 1) Define basic structure of these models 2) Highlight their similarities and differences 3) Define viable paths for improvement CVM-H @ 2000m

  2. SCEC CVM 4.0 (Magistrale, Day, Clayton, & Graves, 2000, 2005) CVM is a rule-based description of crustal velocity structure… • basin velocity descriptions embedded in a regional tomographic (Hauksson, 2000) and 1D background model. • Vp is defined at stratigraphic boundaries as a function of depth(Z) and age (T) using Faust’s law: • relation is calibrated using well control • Vp is linearly interpolated between stratigraphic horizons CVM

  3. SCEC CVM 4.0 (Magistrale et al., 2000, 2005) Features of CVM 4.0 • representation of most major onshore basins • provides top basement and other stratigraphic surfaces that define basin structure • Vs and  defined based on relations with Vp. • geotechnical layer (GTL); lower Vp and Vs values above 300m in basins based on near-surface soil and sediment types and geotechnical boreholes. CVM 4.0

  4. SCEC CVM-H 5.3 (Süss, Plesch, & Shaw, 2003, 2007+) CVM-H is a data- and geostatistical interpolation-based model of crustal velocity structure… • consists of basin velocity descriptions embedded in a regional tomographic model (Hauksson, 2000) • Vp is defined based on tens of thousands of direct velocity measurements from industry sonic logs and seismic reflection data • employs kriging methods to interpolate basin velocity structures CVM-H @ 2000m

  5. Features of CVM-H • representation of major onshore and offshore basins • provides top basement surfaces that defines basin structure • basins structures are consistent with locations and displacements of major faults in CFM • Vs and  defined based on relations with Vp • geotechnical layer (CVM-H 5.3); as implemented in CVM 4.0 SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0

  6. Features of CVM-H • includes lower crust and mantle • lower crust tomographic model consistent with basin velocity structure • teleseismic and surface wave based mantle model is consistent with crustal model • resolution: HR: 250m LR: 1000m CM: 10000m SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0

  7. updates since 2007 annual meeting • 1D background down to 33km • change to Brocher, 2005 for Vp/Vs relation in basins • removal of some local interpolation artefacts with velocities from similar locations • Vs from models in lower crust, mantle SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0

  8. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @+200m

  9. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ sea level

  10. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -500m

  11. SCEC CVM-H 4.0 & 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -1000m

  12. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -2000m

  13. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -4000m

  14. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -6000m

  15. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -15000m

  16. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -20000m

  17. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -20000m

  18. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -32000m

  19. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -34000m

  20. SCEC CVM-H 5.3 (Süss et al., 2003, 2007+) CVM-H 4.0 @ -50000m

  21. What are similarities and differences in these models? Basin structures • both models include most major onshore basins. - Los Angeles - Ventura/San Fernando - Salton trough - … CVM @ 2000m CVM-H @ 2000m

  22. What are similarities and differences in these models? Basin structures • models have broadly similar average velocity functions … CVM-H Vp (CVM 4) CVM Vp (CVM-H 5)

  23. What are similarities and differences in these models? CVM @ -1000m Basin structures • CVM-H includes offshore basins and Santa Maria basin CVM-H @ -1000m

  24. What are similarities and differences in these models? CVM Basin structures • CVM has layers with constant velocity gradients • CVM-H has more complex velocity structures within basins. CVM-H

  25. What are similarities and differences in these models? • CVM-H 4 & 5 include positions and offsets of major faults represented in the CFM w/ faults w/o faults Süss & Shaw (2003, 2005) CVM-H (LA basin)

  26. Future SCEC CVM-H Geotechnical layer • Provide unlimited resolution GTL by standalone code extracted from the CVM Fortran code. • Employ shallow horizons imaged in seismic reflection data to define the base and internal stratification of a new GTL. Los Angeles basin

  27. Request from the USR Focus Group… • encourage user community to employ the latest models that are best suited to their needs … • help us to define ways that models can be improved based on your experiences in using them. How to feed back model perturbation results ? • establish an approach for delivering revised models based on 3D waveform inversion approaches. CVM @ 2000m CVM-H @ 2000m

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