1. J. Louie 4/15/04 Louie, J. N. Scott, J. B. Rasmussen, T. Thelen, W. A. Pancha, A. Clark, M. Park, H. Lopez, C. T. www.seismo.unr.edu/ hazsurv Shallow Shear-Velocity Transects of Urban Areas, and Seismic-Hazard Mapping

2. J. Louie 4/15/04 Transect Results Partly Explain PGA Soil Classes? Weak Soils? Supported by USGS-NEHRP and IRIS-PASSCAL

3. J. Louie 4/15/04 Three Transects Show Geologic Variations

4. J. Louie 4/15/04 Statistics of Geologic Variation  Linear slope in log-log spatial spectrum Fractal variations are probably geological Fractal variations are probably geological  Levels out at end Some variance across <0.6 km is experiment error Some variance across <0.6 km is experiment error

5. J. Louie 4/15/04 V 30 vs Soil Type  Large standard deviations with good averages  Units 3 and 4 well-sampled over long distances

6. J. Louie 4/15/04 V 30 vs Soil Type  Standard deviations increase with sample size  Average velocities of units change along transect

7. J. Louie 4/15/04 Supported by DOE-LLNL and IRIS-PASSCAL Las Vegas Transect

8. J. Louie 4/15/04 Field’s (2001) Amplification Mapping  Needs only basin depth and Vs30  Trial maps made using coefficients from LA Field’s (2001) Amplification Mapping Field; Wald & Mori (2000) B NEHRP -D C

9. J. Louie 4/15/04 Extrapolating Vs30: Las Vegas  Vs30 assigned to soil-map units using transect  Maps don’t predict new measurements- B. Luke, UNLV

10. J. Louie 4/15/04Summary  300 sites on 3 urban transects measured for Vs30.  Vs30 may partly explain PGA, hazard variations.  Long transects show fractal, geologic variations in Vs30.  Geologic, soil maps do not have sufficient Vs30 predictive value for engineering.