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 ([email protected]) Generously Funded by the USGS NEHRP-NIW External Grants Program, Mark Petersen, Regional Coordinator 1

Objectives

 Organize a Nevada community seismic velocity 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 3

Products

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Develop at the workshop: succinct statement of research and data needs that can immediately be included in the next USGS NEHRP-NIW RFP.

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Louie will write (with help) a white paper by March 2008.

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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:  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 5

Last Year’s Nevada Priorities

 Test the sensitivity of shaking to velocity structure at various scales  As a guide to identifying those parts of the velocity model most in need of further study  Use ANSS data in Reno/Carson, and Las Vegas  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 Reno Carson 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  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.

 Develop a regional map of shallow shear velocities and densities from existing measurements for inclusion in the CVM, and for use in ShakeMap.

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  As a guide to identifying those parts of the velocity model most in need of further study  Keep: Use ANSS data in Reno/Carson, and Las Vegas  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 … 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 10

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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-

motion prediction?

• What results do we need in a Nevada CVM for ground 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  13

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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 detail model too few stations for LVV-Pahrump 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  14

Schedule- Tuesday

 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

 Monastero- 3:00- Luke  Vincent 2:00- Moschetti  Rodgers 1:00  Norris 4:00- Magistrale 16

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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?

NV public works board, fire marshall Multi-hazard efforts, emergency managers 17

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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