PowerPoint Presentation - Surveying Seismic Microzonation - PowerPoint by N2WnXf

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									     Surveying Seismic Microzonation in
                Urban Areas
              Using Refraction Microtremor reconnaissance:
                  Rapid surveys take advantage of urban noise
                         More details at www.seismo.unr.edu/hazsurv




Quic kTim e™ and a Motion J PEG OpenDML dec ompressor are needed to s ee this pic ture.




   J. Louie 12/10/2003
Refraction Microtremor for Shallow Shear Velocity
    ReMi measures Rayleigh dispersion with linear
    refraction arrays (paper by Louie, April 2001 BSSA).




                       100-m depth resolution

                                                Initial funding from SCEC, UNR, VUW,
 J. Louie 12/10/2003
                                                Optim LLC
Refraction Microtremor for Shallow Shear Velocity
         ReMi has classified hard and soft sites around the world by
         measuring V30, average shear velocity to 30 m depth.




 J. Louie 12/10/2003
                      Reno Transect
        Local reconnaissance was first test.




                                       Supported by UNR and IRIS-PASSCAL
J. Louie 12/10/2003
                       Reno Transect
        Unexpected results: high V30 in active alluvium.




                                                       Ta




                West                                 East



J. Louie 12/10/2003
                       Reno Transect
Lack of V30
correlation to geologic
or soil maps




                                Only Tertiary Andesite
                                (Ta) shows a
                                characteristic V30

 J. Louie 12/10/2003
      The First Reno Hazard Map




J. Louie 12/10/2003
      Shallow Shear-Velocity Transects
        July 2003 San Gabriel Valley & Los Angeles
                                         B
                                 C

                                                         Transect
                                                         mapped on
                                                         NEHRP
                                                         hazard class
                                                         map by Wills,
                                                         from SCEC
                             D                           Phase 3
                                                         Report

                         E

                                     Supported by USGS, NEHRP ERP and
J. Louie 12/10/2003
                                     IRIS-PASSCAL
                         Los Angeles Transect
           200 shallow Vs profiles from San Gabriel Riv.

San Gabriel Mts.
are C, not B.




                                      V30 may correlate with
                                      hydraulic gradient.




                                                        Alamitos Bay
                                                        is D, not E.

   J. Louie 12/10/2003
                       Los Angeles Transect
No V30 correlation with active vs. older alluvium; R2 = 0.2!




 J. Louie 12/10/2003
Shallow Shear-Velocity Transects
   Las Vegas route from Cheyenne
   to Tropicana

                                               3-km-deep
                                               basin




                                   1-km-deep
                                   basin




Supported by DOE-LLNL and IRIS-
PASSCAL
  J. Louie 12/10/2003
                      Las Vegas Transect
        Some correlation to faulting, soil type?




J. Louie 12/10/2003
                      Las Vegas Transect
        No correlation between V30 and geologic map.




J. Louie 12/10/2003
                      Las Vegas Transect
        Correlation with clay soils, caliche in Las Vegas?




J. Louie 12/10/2003
                          Las Vegas Transect
                Shallow section & V100 hint at stratigraphy, faulting?




                                                                                      Caliche?
                          QuickTime™ and a TIFF (LZW) decompressor are ne eded to see this picture.




                      Fault?

J. Louie 12/10/2003
A Preliminary
 Las Vegas
 Hazard Map

 Transect V30 values
 correlated with soil-
 map units across 4
 quadrangles in Las
 Vegas Valley




 J. Louie 12/10/2003
                                                                   Outreach
        Example of public outreach:
                Discoveries and Breakthroughs Inside Science, news
                shorts funded by AIP, AGU, etc.
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             Technology Transfer: Commercial ReMi is now in use by
             geotechnical consultants and agencies worldwide.

J. Louie 12/10/2003

								
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