Development of Next Generation Attenuation Relationships in the US - - PowerPoint PPT Presentation

1st Kashiwazaki International Symposium on Seismic Safety of Nuclear Installations Niigata Institute of Technology

• Dr. Annie Kammerer

Office of Nuclear Regulatory Research November 2010

Development of Next Generation Attenuation Relationships in the US

• Background, strengths, and features of the models
• Database development
• Ground motion prediction equation (attenuation

relationship) development approaches

• NGA-East project

Overview

Boore et al. (1997)

• In 2003 PEER started a major research program on

Next Generation Attenuation Models for shallow crustal earthquakes in active tectonic regions (high seismicity areas)

• Original program now called “NGA-West”
• NGA-West 2 is on-going with vertical motions,

additional work on uncertainties

• NGA-East started development program in 200 and

full program in 2009

• Both programs coordinated by the Pacific

Earthquake Engineering Research (PEER) Center at University of California Berkeley

Background on NGA Programs

• Different sponsors and some differences in

approaches

• Coordination on the programs on research on:
• Vertical motions
• “Sigma” research, particularly in breaking apart

uncertainties

• New tool for assessing epistemic uncertainty

between the relationships

• Both to be used for USGS National Hazard maps

Background on NGA Programs

• Multi-disciplinary with Broad Interactions
• Geologists
• Seismologists
• Geotechnical Engineers
• Structural Engineers
• Researchers
• Simulation Experts
• Attenuation Relationship Developers
• Users
• Strong database development and research

elements

Strength of the NGA Programs

• Quantity and quality of data
• Next generation development rather than update
• Process
• Interaction among developers
• Strong project coordination
• Public participation via workshops
• Peer Review
• Use of data from similar tectonic settings globally

makes relationships “transportable”

Strength of the NGA Programs

PEER NGA Strong-Motion Database

NGA-West Database

• 173 worldwide shallow

crustal events from active tectonic regions

• 3,551 uniformly

processed strong motion stations

• M 4.2 to 7.9
• 0.5

• Accel. (g)
• 0.5

• Accel. (g)

• 0.5

• Accel. (g)

0.1 1 10 100 1000

Distance (km)

4 5 6 7 8

Magnitude

Previous Data

0.1 1 10 100 1000

Distance (km)

4 5 6 7 8

Magnitude

New Data

• There are more than 100 variables describing

source, path, and site conditions of a record

• NGA-West has 6 distance measures, 4 site classes,

VS30 for most recording sites, Hanging-Wall/Footwall

• Public database at http://peer.berkeley.edu/nga
• NGA-East Database and parameters under

development

• Incorporating data from similar tectonic regions
• West: USA, Japan, Taiwan, Europe, Middle East,

New Zealand, Latin America

• East: USA, Canada, Australia, South Africa, etc

PEER NGA Strong-Motion Database

• Magnitude scaling
• Distance scaling
• Linear and nonlinear soil response
• Depth to basement rock (NGA-west)
• Fault mechanism: strike-slip, reverse, normal

faulting

• Horizontal and vertical motions
• Complete characterization of uncertainties

Key Features of the GMPE Models

• NGA-West used mostly empirical approach due to

the extensive new database available. Some hybrid (with simulation) approaches were used.

• Because of the lack of a large strong motion

dataset for central and eastern North America, a significant simulation database must be developed for NGA-East.

• A significant research effort is also needed to better

define inputs to simulation, to undertaken the simulations, to develop the GMPEs, and to characterize uncertainties

GMPE Development Background

• Multi-sponsor project
• Moment Magnitude 4-8
• Distances of 0-1000 km
• Horizontal and Vertical
• Spectral periods 0.01-10 sec
• Full characterization of uncertainties
• SSHAC (NUREG/CR-6372) Level 3 Study
• Coordinated with CEUS Seismic Source

Characterization Project for Nuclear Facilities

NGA-East

• 1. Compilation of available ground motion data in

CENA and relevant data in other Regions

• 2. Identification and evaluation of currently available

simulation methods

• 3. Application of selected simulation methods to

develop a database of simulated ground motions

• 4. Assessment of required input parameters
• 5. Development of suites of alternative GMPEs for

median ground motion that capture the range of simulations methods and capture the uncertainty in the input parameters to each simulation method

NGA-East Major Tasks

• 6. Development of suites of alternative models for

the single-station standard deviation and generic standard deviation (i.e., sigma)

• 7. Development of weights on the logic tree for the

alternative GMPE (median) and alternative aleatory variability models

• 8. Development of a method for vertical motions
• 9. Development of a method for site response
• 10. Documentation of project activities and outcomes

NGA-East Major Tasks

Initial Development by Working Groups

Recorded Databases

seismicity data, geotechnical data, and crustal models collected

SSHAC Workshops

Seismic Parameter Technical Basis

Research to develop basis for range of inputs & development

• f alternate proponent models where appropriate (e.g., Q,

geometrical spreading, site response, stress drop, Kappa, slip distributions, rupture velocity, and appropriate correlations)

Simulation Databases

Preliminary point source simulations undertaken (Initial parameter estimates from TI team), Validations approaches for simulations determined

Recorded Databases

Content of seismicity catalogue presented and discussed. Definition

• f base rock and project crustal

models for simulations determined through workshop input.

Parameter Community Distributions

Distributions of parameters and their correlations developed through proponent-based discussions at

• workshops. Resulting “community distributions”

developed that reflect the center, body and range of the informed technical community.

Simulation Databases

Refinement of point source simulations & approach to finite fault source simulations finalized incorporating community input from workshops

Final Simulation Database Development

Full set of simulations undertaken after RFP process to identify 1 point source team and 3 finite fault source teams (to capture epistemic). Simulation sets used by simulation teams and specified based on Parameter Community Distributions. (see Figure 3)

Simulations SSHAC Workshops

GMPE Approaches for RFPs Defined

Sets of approaches to be included in RFP determined based on input (e.g., data set, functional form, and magnitude scaling constraints) developed during workshops in order to appropriately capture epistemic uncertainty. (see figure 4)

GMPE Input Database Review

Simulation and Seismicity Databases reviewed and sets of data for GMPE development selected. RFPs for GMPE teams will specify data to be used in the development of various community models.

GMPE Review & Finalization & Guidance Development

GMPE Suite Developed

Teams will participate in interactive GMPE developer workshops leading to a suite of community GMPEs

GMPE Development

GMPE Suite and Guidance Finalized

Suite of GMPEs will be evaluated, including an assessment using the Scherbaum tool Final GMPE suite and logic tree weights chosen Guidance and documentation developed

Figure 1: Conceptual Approach for NGA-East Rock GMPE Development

Site Response Vertical Motions

Project Participants

• Technical Integration Team
• Participatory Peer Review Panel
• Project Management
• Joint Management Committee (sponsors)
• Scientific Working Groups
• Database, Simulations, Source and path effects,

Sigma, Vertical, Geotechnical, GMPE

• Specialty contractors and resource experts
• Currently approximately 60 participants, with more

expected by the end of the project

• International team from USA, Canada, Australia,

Germany, Turkey, Italy, and the United Kingdom

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THANK YOU