NGA-East Station Database Draft Site Metadata: V S30

Transcription

1 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

2 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

3 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

4 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 Updated Internal Release Station Database 4

5 DATA SOURCES OF V S30 Measurement Source Count Beresnev, I. A., and Atktinson, G. M 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 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

6 PROXY-BASED ESTIMATIONS OF V S30 Available Proxies: Geology by Kottke et al 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 Estimates (100%) Terrain by Yong et al Estimates (99%) Estimates not available at remaining locations Hybrid Slope-Geology by Thompson and Silva Estimates (100%) P-Wave Seismogram by Kim et al 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

7 PROXY-BASED ESTIMATIONS OF V S30 Available Proxy-based estimations of V S30 7

8 OLD: PROXY EVALUATION Compare V S30 data with Estimates Residual R ln ln, 0.6 Geology Terrain Slope P-Wave (>1) Hybrid S-G R 0.4 Model bias as mean of residuals = μ ln(v) Standard deviation of residuals = σ ln(v) R R 8

9 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

10 PREFERRED V S30 Code 4 Assignment Relative Proxy μ ln(v) σ ln(v) Count Weight Weight Geology Terrain Slope Hybrid Pwave Code 5 Assignment Relative Proxy μ ln(v) σ ln(v) Count Weight Weight Geology Terrain Slope Hybrid 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

11 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 YES 0.63 Terrain YES 0.37 Slope NO - Hybrid 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/

12 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) = 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) = 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

13 PREFERRED V S30 13

14 PREFERRED V S30 LOCATIONS V S30 (m/s) 14

15 PREFERRED V S30 CODE ASSIGNMENT 15

16 PREFERRED V S30 MEASUREMENT COUNTS V S30 (m/s) Count Recommended V S30 (m/s) 16

17 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

18 ACKNOWLEDGMENTS PEER EPRI MRCE Cheryl Moss Sissy Nikolaou Alan Yong Eric Thompson David Wald Vince Quitoriano Lian Fan 18

19 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, 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., 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), 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

20 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), 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), 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 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 , February