NGA-East Station Database Draft Site Metadata: V S30 Youssef. M. A. Hashash, Joseph Harmon, Jonathan P. Stewart, Albert Kottke, Byungmin Kim, Walt Silva, Ellen Rathje, Kenneth W. Campbell 14 July 2014
OUTLINE Scope of GWG contribution to the Station Database (StDB) Data Sources and Distribution of V S30 Proxy-Based Estimations of V S30 Slope Geology Terrain P-Wave Hybrid Slope-Geology Preferred V S30 Selection of V S30 Uncertainty Summary Relevant References 2
SCOPE OF STATION DATABASE V S30 (STDB) Format of StDB and preferred V S30 estimation follows NGA-West2 Site Database: Seyhan, E., J. P. Stewart, T. D. Ancheta, R. B. Darragh and R. W. Graves (2014). "NGA-West 2 site database." Earthquake Spectra (In review). NGA-East Station Database does not include Basin depth parameters or models Regional considerations 3
SCOPE OF STATION DATABASE (STDB) 1375 station locations with accompanying metadata (where available) Name Instrument Measured V S30 Geology Information GWG Geology Classification Site-Specific (USGS or other) Geologic information Estimated V S30 values by proxy Preferred V S30 and σ ln(vs30) Estimates Current version is built from 2014-04-15 Updated Internal Release Station Database 4
DATA SOURCES OF V S30 Measurement Source Count Beresnev, I. A., and Atktinson, G. M. 1997 9 CERI; Paul Mayne 9 Dames and Moore (1974) 1 EPRI (2013) 33 Ghofrani et al, 2014, in preparation 1 GSC station book 1 Herrmann and Crosley (2008) 1 Jaume (2006) 5 Lin, L. and Adams, J. 2010/05/28 1 Karen Assatourians- Personal Communication 2 Flatfile (unknown) 2 Odum et al (SRL draft); USGSDGM 5 Read et al (2008) 2 St Louis Univ. 4 USGS (ANSS sta) 2 USGS Mineral, Virginia Earthquake Site Investigation 2013 1 Williams et al (2003) 5 84 Sites (6%) have V S30 Measurements Major sources of measurements: EPRI 33 (39%) Beresnev and Atkinson 9 (11%) CERI; Paul Mayne 9 (11%) 5
PROXY-BASED ESTIMATIONS OF V S30 Available Proxies: Geology by Kottke et al. 2012 Proxy by GWG Geology classes 1083 Estimates (79%) by site-specific geology 292 Estimates (21%) by global average (no NGA-GWG Geology type available) Slope by Wald and Allen 2007 1375 Estimates (100%) Terrain by Yong et al. 2012 1367 Estimates (99%) Estimates not available at remaining locations Hybrid Slope-Geology by Thompson and Silva 2013 1375 Estimates (100%) P-Wave Seismogram by Kim et al. 2014 123 sites with one estimate from one record (9%) 81 sites with estimates from multiple records (6%) Proxy V S30 is an arithmetic mean of all estimates at a site 6
PROXY-BASED ESTIMATIONS OF V S30 Available Proxy-based estimations of V S30 7
OLD: PROXY EVALUATION Compare V S30 data with Estimates Residual R ln ln, 0.6 Geology Terrain Slope 0.4 0.2 0 0.6 P-Wave (>1) Hybrid S-G -2-1 0 1 2 R 0.4 Model bias as mean of residuals = μ ln(v) Standard deviation of residuals = σ ln(v) 0.2 0-2 -1 0 1 2 R -2-1 0 1 2 R 8
PREFERRED V S30 Preferred V S30 estimate assigned to stations by weighting proxies by one of the following procedures: 0 Assign V S30 from measurement 1 Assign from known site conditions and measurements on similar geology in the area. Based on site visit or and/or geologist recommendation 2 P-wave Seismogram if predicted V S30 from multiple estimates > 760 m/s 3 Hybrid Slope-Geology if predicted V S30 > 760 m/s 4 Infer by weighting V S30 estimates by geotechnical proxy if multiple estimates by p-wave seismogram (as in Kim et al. (2014)) are available 5 Infer by weighting V S30 estimates by geotechnical proxy if no estimates of V S30 by p-wave seismogram (as in Kim et al. (2014)) are available Relative weights assigned by comparison of estimates to measurements Relative weight for each proxy = 9
PREFERRED V S30 Code 4 Assignment Relative Proxy μ ln(v) σ ln(v) Count Weight Weight Geology 0.079 0.479 34 4.24 0.27 Terrain 0.375 0.567 34 2.16 0.14 Slope 0.300 0.593 34 2.27 0.15 Hybrid 0.297 0.571 34 2.41 0.15 Pwave -0.109 0.456 34 4.54 0.29 Code 5 Assignment Relative Proxy μ ln(v) σ ln(v) Count Weight Weight Geology 0.068 0.508 84 3.80 0.36 Terrain 0.373 0.612 84 1.94 0.19 Slope 0.254 0.613 84 2.27 0.22 Hybrid 0.245 0.592 84 2.43 0.23 0.4 0.2 0-0.2-0.4 0.8 0.7 0.6 0.5 0.4 0.3 Residual at Stations with all Proxies (Code 4) Residual of Proxies at Stations where measurements are available (Code 5) Geology Terrain Slope Hybrid Pwave 10
PREFERRED V S30 MISSING DATA For locations missing proxies, weights adjusted to sum to unity Example: Code 5 Assignment Ex: Proxy μ ln(v) σ ln(v) Count Missing V S30 estimates by proxy: Missing P-Wave (81/1375): Relative Weight Weight Available? New Weight Geology 0.068 0.508 84 3.80 0.34 YES 0.63 Terrain 0.373 0.612 84 1.94 0.20 YES 0.37 Slope 0.254 0.613 84 2.27 0.23 NO - Hybrid 0.245 0.592 84 2.43 0.24 NO - Multiple ground motion recordings required for estimation of V S30 123/1376 Stations with only one estimate are included in database, but not used for developing Preferred V S30 Not all sites have classifiable terrain Hybrid 1375/1375 Slope 1375/1375 Terrain 1367/1375 Geology 1375/1375 11
PREFERRED V S30 STD. DEVIATION Standard Deviation (σ ln(v) )on Preferred V S30 assigned by similar weighting procedure Code 0 sites (sites with geotechnical measurement of V S30 ) σ ln(v) = 0.1 - Judgment From NGA-West 2 recommendation of σ ln(v) on measurements Code 1 (Known site condition from site visit or geology) σ ln(v) = 0.3 - Judgment Code 2 and 3 (P-wave only or Hybrid only) Use σ ln(v) for P-wave (code 2) or Hybrid (code 3) from the residuals for the 34 sites with all proxies Code 4 and 5 Weight σ ln(v) same as V S30 12
PREFERRED V S30 13
PREFERRED V S30 LOCATIONS V S30 (m/s) 14
PREFERRED V S30 CODE ASSIGNMENT 15
PREFERRED V S30 MEASUREMENT COUNTS 20 16 12 8 4 0 500 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 V S30 (m/s) Count 400 300 200 100 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 Recommended V S30 (m/s) 16
SUMMARY OF V S30 ASSIGNMENT Station V S30 measurements and estimates by proxy compiled into Station Database Procedure developed for assigning Preferred V S30 and σ ln(vs30) estimates 17
ACKNOWLEDGMENTS PEER EPRI MRCE Cheryl Moss Sissy Nikolaou Alan Yong Eric Thompson David Wald Vince Quitoriano Lian Fan 18
REFERENCES Ancheta, T.D., Darragh, R.B., Stewart, J.P.,Seyhan, E., Silva, W.J., Chiou, B.S.J., Woodell, K.E., Graves, R.W., Kottke, A.R., Boore, D.M., Kishida, T. and Donahue, J.L. (2013). PEER NGA-West 2 database, PEER Report 2013/03, Pac. Earthq. Eng. Res. Ctr, Berkeley, CA. Beresnev, I. A., and G. M. Atkinson (1997). Shear-wave velocity survey of seismographic sites in eastern Canada: calibration of empirical regression method of estimating site response. Seism. Res. Lett. 68, 981 987. Electric Power Research Institute (EPRI) (2004, 2006) (2013) "Ground-motion model (GMM) review project: Shear wave velocity measurements at seismic recording stations." Palo Alto, Calif.: Electric Power Res. Inst., 3002000719. Jaume, S.C. (2006). Shear-wave velocity profiles via seismic cone penetration test and refraction microtremor techniques at ANSS strong motion sites in Charleston, South Carolina. Seis. Res. Lett., 77(6), 771-779. Kim, B., Y. M. A. Hashash, E. M. Rathje, J. P. Stewart, S. Ni, P. G. Sommerville, A. R. Kottke, W. J. Silva, and K. W. Campbell (2014). Subsurface Shear-wave velocity characterization using P-wave seismograms in Central and Eastern North America (in press) Kottke,A.R.,Y.M.A.Hashash,J.P.Stewart,C.J.Moss,S.Nikolaou,E.M.Rathje,W.J.SilvaandK. W. Campbell (2012). Development of geologic site classes for seismic site amplification for Central and Eastern North America. 15th World Conference in Earthquake Engineering (WCEE). Lisbon, Portuga 19
REFERENCES Odum, J.K., R.A. Williams, W.J. Stephenson, and D. M. Worley (2010). Shallow seismic velocity and Vs30, at 5 ANSS sites in Southern Illinois and Evansville, Indiana. SRL Draft. Read, K. H. El. Naggar, and D. Eaton (2008). Site-response spectra for POLARIS station sites in Southern Ontario and Quebec. Seis. Res. Lett., 79(6), 776-784. Seyhan, E., J. P. Stewart, T. D. Ancheta, R. B. Darragh and R. W. Graves (2014). "NGA-West 2 site database." Earthquake Spectra (In review). Thompson, E. and W. Silva. Development of a Hybrid Slope-Geology Method of Estimating Vs30 for Central and Eastern North America (in press) Wald, D.J. and T. I. Allen (2007). Topographic slope as a proxy for seismic site conditions and amplification. Bull. Seism. Soc. Am., 97(5), 1379-1395. Williams, R.A., W.J. Stephenson, J.K. Odum, and D.M. Worley (2003). Seismic velocities from highresolution surface-seismic imaging at six ANSS sites near Memphis, Tennessee. USGS Open-File Report 03-218. Yong, A., S. E. Hough, J. Iwahashi, and A. Braverman (2012). A terrain-based site characterization map of California with implications for the Contiguous United States. Bulletin of the Seismological Society of America, Vol. 102, No. 1, pp. 114 128, February 2012 20