J. Louie 9/5/2005 OutlineOutline 1.Refraction Microtremor for Shallow Vs 2.ReMi-Borehole Comparison...
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Transcript of J. Louie 9/5/2005 OutlineOutline 1.Refraction Microtremor for Shallow Vs 2.ReMi-Borehole Comparison...
J. Louie 9/5/2005J. Louie 9/5/2005
OutlineOutlineOutlineOutline
1.1. Refraction Microtremor for Shallow VsRefraction Microtremor for Shallow Vs
2.2. ReMi-Borehole ComparisonReMi-Borehole Comparison
3.3. Los Angeles TransectLos Angeles Transect
4.4. Las Vegas TransectLas Vegas Transect
5.5. Effect of Shallow Vs on Shaking ModelsEffect of Shallow Vs on Shaking Models
1.1. Refraction Microtremor for Shallow VsRefraction Microtremor for Shallow Vs
2.2. ReMi-Borehole ComparisonReMi-Borehole Comparison
3.3. Los Angeles TransectLos Angeles Transect
4.4. Las Vegas TransectLas Vegas Transect
5.5. Effect of Shallow Vs on Shaking ModelsEffect of Shallow Vs on Shaking Models
J. Louie 9/5/2005J. Louie 9/5/2005
Building a Las Vegas Seismic ModelBuilding a Las Vegas Seismic ModelBuilding a Las Vegas Seismic ModelBuilding a Las Vegas Seismic Model
J. Louie 9/5/2005J. Louie 9/5/2005
Model Rendered as Amplification MapModel Rendered as Amplification Map Geology, Basin Depth, Geotech, Geophysical data into Geology, Basin Depth, Geotech, Geophysical data into ModelAssemblerModelAssembler
Las VegasBasinLas VegasBasin
LittleSkull Mtn.LittleSkull Mtn.
DeepVolcanicRifts
DeepVolcanicRifts
J. Louie 9/5/2005J. Louie 9/5/2005
Max. Ground Motion Computed– 0.1 HzMax. Ground Motion Computed– 0.1 Hz E3D elastic finite-difference solution, by Shawn Larsen, LLNLE3D elastic finite-difference solution, by Shawn Larsen, LLNL
Las VegasBasinLas VegasBasin
LittleSkull Mtn.LittleSkull Mtn.
DeepVolcanicRifts
DeepVolcanicRifts
J. Louie 9/5/2005J. Louie 9/5/2005
Detailed Model Makes a Difference- even at 0.1 HzDetailed Model Makes a Difference- even at 0.1 Hz Max. ground motion ratio, models with and without geotechnical modelMax. ground motion ratio, models with and without geotechnical model
LittleSkull Mtn.
Las VegasBasinLas VegasBasin
J. Louie 9/5/2005J. Louie 9/5/2005
Detailed Model Makes a DifferenceDetailed Model Makes a Difference But not in any way that can be predicted from the model alone– basin But not in any way that can be predicted from the model alone– basin
geometry, source, and propagation path all matter!geometry, source, and propagation path all matter!
73% predicted for 2-4 Hz73% predicted for 2-4 Hz 6% computed for 0.1 Hz6% computed for 0.1 Hz
J. Louie 9/5/2005J. Louie 9/5/2005
Max. Ground Motion Computed– 0.5 HzMax. Ground Motion Computed– 0.5 Hz E3D elastic finite-difference solution, by Shawn Larsen, LLNLE3D elastic finite-difference solution, by Shawn Larsen, LLNL
Las VegasBasinLas VegasBasin
LittleSkull Mtn.Little
Skull Mtn.
DeepVolcanicRifts
DeepVolcanicRifts
J. Louie 9/5/2005J. Louie 9/5/2005
Comparing Computed GM at 0.5 HzComparing Computed GM at 0.5 Hz At UNLV in the southern part of LVV, there are unexpected waveform At UNLV in the southern part of LVV, there are unexpected waveform
differences, even with the similar maximum motions.differences, even with the similar maximum motions.
J. Louie 9/5/2005J. Louie 9/5/2005
Comparing Computed GM at 0.5 HzComparing Computed GM at 0.5 Hz In central Las Vegas Valley, the detailed model has lower velocities In central Las Vegas Valley, the detailed model has lower velocities
(0.35 km/s) than the 0.5 km/s Vs30 assumed for basins.(0.35 km/s) than the 0.5 km/s Vs30 assumed for basins.
Detailed LVV ModelDetailed LVV Model Basin Vs30=0.5 km/s ConstantBasin Vs30=0.5 km/s Constant
J. Louie 9/5/2005J. Louie 9/5/2005
Detailed Model Makes a Difference at 0.5 HzDetailed Model Makes a Difference at 0.5 Hz Max. ground motion ratio, models with and without geotechnical modelMax. ground motion ratio, models with and without geotechnical model
LittleSkull Mtn.
Las VegasBasinLas VegasBasin
J. Louie 9/5/2005J. Louie 9/5/2005
Detailed Model Makes a Difference- at 0.5 HzDetailed Model Makes a Difference- at 0.5 Hz In a way that can be partly predicted from the model alone– but basin In a way that can be partly predicted from the model alone– but basin
geometry, source, and propagation path still matter at 0.5 Hz.geometry, source, and propagation path still matter at 0.5 Hz.
73% predicted for 2-4 Hz73% predicted for 2-4 HzUp to 213% computed for 0.5 HzUp to 213% computed for 0.5 Hz
J. Louie 9/5/2005J. Louie 9/5/2005
Conclusions IIConclusions IIConclusions IIConclusions II
In tectonic areas, the regional In tectonic areas, the regional
distribution of distribution of basinsbasins affects shaking. affects shaking.
We have built a We have built a ModelAssemblerModelAssembler for for
Nevada to create 3-d computation grids Nevada to create 3-d computation grids
from geological and geotechnical data.from geological and geotechnical data.
Surprisingly, geotechnical Surprisingly, geotechnical detailsdetails affect affect
even 10-sec computations in ways even 10-sec computations in ways
difficult to forecast.difficult to forecast.
In tectonic areas, the regional In tectonic areas, the regional
distribution of distribution of basinsbasins affects shaking. affects shaking.
We have built a We have built a ModelAssemblerModelAssembler for for
Nevada to create 3-d computation grids Nevada to create 3-d computation grids
from geological and geotechnical data.from geological and geotechnical data.
Surprisingly, geotechnical Surprisingly, geotechnical detailsdetails affect affect
even 10-sec computations in ways even 10-sec computations in ways
difficult to forecast.difficult to forecast.