Science for a changing world

The USGS The USGS and the Development of theand the Development of the

Nevada Great Basin Community Nevada Great Basin Community Velocity ModelVelocity Model

Science for a changing world

ObjectivesObjectives

Help Coordinate efforts between UNLV, Help Coordinate efforts between UNLV, UNR, USGS, others, to develop a UNR, USGS, others, to develop a Community Velocity Model (CVM) Community Velocity Model (CVM) patterned after Wasatch CVM effortpatterned after Wasatch CVM effort

Make CVM available to public when Make CVM available to public when completedcompleted

Develop Urban Seismic Hazard Maps for Develop Urban Seismic Hazard Maps for Reno and Las Vegas Metropolitan AreasReno and Las Vegas Metropolitan Areas

Science for a changing world

USGS Open-File Report 2007-1175 http://pubs.usgs.gov/of/2007/1175

Seattle 3D Vs Velocity Model Seattle 3D Vs Velocity Model used in Seattle Urban Seismic Hazard Mapsused in Seattle Urban Seismic Hazard Maps

Vs (m/s)

N

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Urban Seismic Hazard MapUrban Seismic Hazard Map

1 Hz S.A. (%g) with 2% Prob. Of Exceedance in 50 Years

2002 National Seismic Hazard Map w/ NEHRP Amplification factors

based on Vs30

New map w/ ground motion simulation results (basin effects, rupture directivity, and nonlinear soil response at soft-soil

sites)

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Information Important in Developing Information Important in Developing Community Velocity ModelsCommunity Velocity Models

(not inclusive and area dependent)(not inclusive and area dependent)

Regional Geology (including basin Regional Geology (including basin Quaternary units and all active faults)Quaternary units and all active faults)

Realistic Basin Geometry (from gravity, Realistic Basin Geometry (from gravity, seismic tomography, boreholes, etc.)seismic tomography, boreholes, etc.)

Geotechnical Data (borehole)Geotechnical Data (borehole)

Geophysical Data (Vs, Vp, density, Geophysical Data (Vs, Vp, density, attenuation, etc.)attenuation, etc.)

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Possible Steps for Research Possible Steps for Research Community to Reach Objectives Community to Reach Objectives Coordinate the compilation of all existing Coordinate the compilation of all existing relevant data (how much data is there?)relevant data (how much data is there?)Develop model with existing data (using Develop model with existing data (using searchable code (e.g. Wasatch CVM) , searchable code (e.g. Wasatch CVM) , ModelAssembler, 3ModelAssembler, 3rdrd party 3D software) party 3D software)Model validation (determine what additional data Model validation (determine what additional data is needed, where is it most needed)is needed, where is it most needed)Acquire new data/incorporate into ModelAcquire new data/incorporate into Model

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Funding (???)Funding (???)

Dependent on Funding levels from CongressDependent on Funding levels from Congress

Historically, ~$120k has been available for these Historically, ~$120k has been available for these type of efforts every year in type of efforts every year in National/Intermountain West panelsNational/Intermountain West panels

Translates into ~1-2 proposals funded annuallyTranslates into ~1-2 proposals funded annually

USGS has historically collaborated on data USGS has historically collaborated on data acquisition with internal funding and anticipates acquisition with internal funding and anticipates doing so, if neededdoing so, if needed

Science for a changing world

Science for a changing world

Wasatch FrontWasatch FrontStacked Migrated Seismic Depth SectionStacked Migrated Seismic Depth Section

Processing Datum = 1450 m

Vertical exag. 2:1Vertical exag. 2:1

WW EE

200200

400400

600600

800800

10001000

12001200

Dep

th (

m)

Dep

th (

m)

elevationelevation

Science for a changing world