Nevada Great Basin
Community Velocity Model
Workshop
Welcome from All of Us
at the Nevada Seismological Lab:
Convenor: J. Louie (cell 775-229-3835)
Arrangements: Lori McClelland (mcclella@unr.edu)
Generously Funded by the USGS NEHRP-NIW External Grants
Program, Mark Petersen, Regional Coordinator
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Objectives

Organize a Nevada community seismicvelocity modeling effort for the western Great
Basin

Goal is predicting earthquake ground motions
in urban areas and other sensitive sites.

The CVM will:


address seismic velocities at the crustal, basin, and
geotechnical scales; and
contribute directly toward an overall Great Basin
Community Velocity Model.
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Objectives (cont.)

Will hear from experts who have constructed
other CVMs

Assess what CVM features most affect
predicted ground motions

Prioritize our needs for geological and velocity
data

We are not assessing sources
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Products
 Develop
at the workshop: succinct
statement of research and data needs
that can immediately be included in the
next USGS NEHRP-NIW RFP.
 Louie will write (with help) a white paper
by March 2008.
 Available at the
www.seismo.unr.edu/gbcvm website to
those writing NEHRP proposals.
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Last Year’s Nevada Priorities

Improve and validate 3D velocity models
needed for waveform modeling of the effects of
basin- and near-surface-geology:


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For Reno-Carson City, and Las Vegas
Using a variety of techniques including Vs30,
tomography, inversion of seismograms, correlations
with incorporation of geology, etc.
Incorporate results into the Community Velocity
Model
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Last Year’s Nevada Priorities

Test the sensitivity of shaking to velocity structure
at various scales


Use ANSS data in Reno/Carson, and Las Vegas


As a guide to identifying those parts of the velocity
model most in need of further study
To find empirical site response, validate predictions of
3D velocity models, and improve ground motion
prediction approaches.
Prepare scenario ground motion models based
on waveform modeling

For earthquakes on major faults affecting
Reno/Carson and Las Vegas.
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Next Year’s Nevada Priorities

Develop a Western Basin & Range CVM:


To cover the entire region with existing geological and
geophysical information, plus embedded details for the RenoCarson City Urban Corridor (including Tahoe), and the Las
Vegas Metro area (including Pahrump Valley).
Validate the CVM during its development by generating
synthetics from the 3-d model for recordings of moderate
earthquakes and explosions. Revise the model to incorporate
validation results.
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Next Year’s Nevada Priorities

Develop new data for incorporation into the Western Basin &
Range CVM:
• Western Basin & Range Region
 Develop a regional map of shallow shear velocities and densities
from existing measurements for inclusion in the CVM, and for use in
ShakeMap.
• Las Vegas Metro Area (including Pahrump Valley)
 Construct a model for the structure of the edges of the Pahrump
basin, consistent with fault models, for inclusion in the CVM.
 Obtain generalized depths of important impedance contrasts in Las
Vegas Valley for inclusion in the CVM.
• Reno/Carson City Urban Corridor (including Tahoe)
 Construct cross sections of the significant basins, consistent with
available geological and geophysical data sets, for inclusion in the
CVM.
 Collect shallow Vs measurements at uncharacterized ANSS sites,
and on geologic units not well characterized.
 Compile and develop a detailed shallow shear-velocity model for the
Urban Corridor using existing geological and geophysical data.
 Obtain generalized depths of important impedance contrasts in the
Urban Corridor.
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Next Year’s Nevada Priorities

Delete: Test the sensitivity of shaking to velocity structure
at various scales


Keep: Use ANSS data in Reno/Carson, and Las Vegas


As a guide to identifying those parts of the velocity model most in
need of further study
To find empirical site response, validate predictions of 3D velocity
models, and improve ground motion prediction approaches.
Update: Prepare scenario ground motion models based
on waveform modeling with the Western Basin & Range
CVM.

For earthquakes on major faults affecting Reno/Carson and Las
Vegas.
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Schedule- Monday AM

8:00 Louie Introduction, thanks, and workshop objectives

Status of CVM efforts in Nevada

8:20 Louie Crustal thickness in the northern Sierra and northern Nevada

8:40 Anderson Need for accurate velocity models in NV network seismol

9:00 von Seggern Joint seismic tomography/relocation, Reno-Carson

9:20 Rodgers 3-d models of the southern Great Basin, and shaking in LV

10:20 Luke Shear wave velocity profiling in Las Vegas valley

10:40 Pancha Need for an accurate Reno velocity model …

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11:00 Henry Three-dimensional geologic complexity of the Truckee
Meadows basin from geologic mapping
11:20 Liberty Geophysical characterization of the Hot Creek Valley, central
Nevada
11:40 Moschetti Application of empirical Green's functions in the
construction and validation of the Great Basin CVM
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Schedule- Monday PM
1:30 Louie The MA-CME modeling environment and initial scenario
ground-motion computations for Reno and Las Vegas
USGS objectives, funding, internal & external projects, and collaborations

1:50 Odum NEHRP-NIW priorities, funding, internal projects and the
Nevada CVM
Status and results of Utah CVM

2:10 Magistrale The Wasatch Front CVM
Other CVM efforts- their advice

2:40 Sydnor Applications of shear-wave velocity to the Building Code

3:00-3:40 Break for coffee and discussion

3:40 Wills Preparing maps of Vs30 based on geologic maps

4:10 Rodgers The 1906 modeling effort, and lessons learned

4:40 Louie for Keller Open Earth Framework: Building 3-d models via
integration of geological and geophysical data

4:50 Louie CVM efforts in Wellington, New Zealand
5:00 Questions, wrap-up, charge for Tuesday discussions
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Schedule- Tuesday

8:00-9:40 Discussion- What results do we need in a Nevada CVM for
ground-motion prediction?
• We will have an “Official Version”. Datasets are included if difference is
significant when tested by CVM group.
• Regional
 1. P-wave tomography- start w/ Hearn- add Preston, Biasi, S. NV,
gravity (Jachens)
 1. Exists: crustal Vs model from TA-EGF (Morgan)
 1. Basin geometry
 What is the database- collaborations? Earthvision, MA-CME (some
devel. Needed), Magistrale code- merging/smoothing?
 1. Geotech layer
 2. Geotech Wills, scope out- ShakeMap, MX Missile files
 2. Catalog of fault dips (add to Qfaults?), Geology (structure and
stratigraphy) of basin edges- collaboration with DOE-geothermal?
 2. Rework of Jachens regional basin gravity with better fault dips
• Model uncertainties- subject for NSF, DOE proposals? How to honor
needs of ultimate customers?
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Schedule- Tuesday

8:00-9:40 Discussion- What results do we need in a Nevada CVM for ground-
motion prediction?
• Reno/Carson City Urban Corridor
 1. 3-d Geology of basin floor and edges- fault models-> define cross section
(1. Carson Range fault system simple geometry model; 2. Basin east-side
faults)
 1. assemble existing sections through Reno and Carson Val. (Cashman,
Henry)
 1. Abbott basin model- Reno, Eagle Val.- products available from Washoe
Co.
 2. Oppliger Carson Val. gravity database modeling
 2. Carson Range fault system model development-USGS collab
 1. Tahoe Basin model, Karlin, UCSD
 2. Remodeling of reno basin, including new wells, Washoe Co. gravity
 1. Geotech layer- Louie, Pancha
 1. Vs at Carson-Valley ANSS, unmeasured geologic units (by USGS?),
Geotech data correlation with Geology
 1. P-S tomography from Preston
 1. R1, R2, R3 from reflection by USGS? Stephenson-UNLV collab?
 1. Deep basin (>100 m) Vs from UNR (funded FY’08)
 2. Soil nonlinearity- assembly plus new models
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Schedule- Tuesday
• Las Vegas Metro Area (incl. Pahrump Val.)
 1. Geology of Pahrump basin edges- fault models
 1. Langenheim basin model- LVV.
 2. Roach Val., Coyote Springs basin models
 2. Pahrump basin model from D. Donovan, Hoffard?
 1. Geotech layer- Louie, Luke
2. Nellis assessments (collab w/ Air Force), Geotech correlation with
Geology from UNLV? Vs at ANSS sites (w/ USGS?)
 1. Hearn, Moschetti P-S tomography- too few stations for LVV-Pahrump
detail model
 1. R1, R2, R3, reflection, refraction LVV (Snelson), Pahrump from D.
Donovan, Hoffard theses?
 1. Deep basin (>100 m) Vs from UNLV 2. Vetted & improved, interstation
phase vel, EGF, Abbott’s Pahrump array- collaboration
 Collaborations- New seismic stations for tomography and site response
 2. Soil nonlinearity- assembly plus new models
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Schedule- Tuesday
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Who will use the CVM, and how?
Simulators, validators
Who does model assembly? Framework?
• Eastern California, Nevada, Utah CVM; Western
Basin & Range CVM
• MA-CME adopts Magistrale subroutines
• Someone assembles refs and sections, rules and 1-d
profiles, geotech layers, DOE & YM info?

Who does synthetics and validation? Code?
• Collaborative project with Olsen?
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Airport times
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Monastero- 3:00- Luke
Vincent 2:00- Moschetti
Rodgers 1:00Norris 4:00- Magistrale
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Schedule- Tuesday

10:20-12:00 Discussion
How do we obtain the necessary data and results?

What methods are cost-effective enough to be funded?

What collaborations are needed?

Need a document to take to potential funders
• White paper to USGS, report on meeting to NESC Feb
• Version, vetted by NESC May, for forums in Reno, LV, including (what
will they get out of it):
• USGS volcano, groundwater wat res
• Utilities: SPPCo, Nevada Power, TMWA, SNWS, SNWA
• FEMA (security of Dam, CA power trans), NV-DEM, ACE, USBurRec,
Army (commander of Hawthorne), Navy, Air Force (LVV-Nellis base
engineer colonel- mission integrity & force readiness)
• Gas pipelines, oil pipelines
• Builders: NNBA, WNBA, SNBA- AEG regions
• NRC
• NDOT
• DOE- YMP, NNSA, GMSEC- NSO
• AEG, ASCE, SEASoN, Reno & Las Vegas Chapt.; AIA?
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• NV public works board, fire marshall
Schedule- Tuesday

12:00-3:00 Working lunch and Discussion Write and order Nevada CVM priorities for NEHRP RFP

3:00 Adjourn
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