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
NGA-West Database • 173 worldwide shallow 8 8 crustal events from active tectonic regions 7 7 • 3,551 uniformly Magnitude Magnitude processed strong 6 6 motion stations • M 4.2 to 7.9 5 5 2002 Denali (Alaska) EQ, Pump Station 10 0.5 PS10, 47 Deg. Accel. (g) 1.5 4 4 0.0 Spectral Acceleration (g) 0.1 0.1 1 1 10 10 100 100 1000 1000 1 -0.5 0.5 Distance (km) Distance (km) PS10, Vertical Accel. (g) 0.0 0.5 Previous Data New Data -0.5 0.5 0 PS10, 317 Deg. 0.01 0.1 1 10 Accel. (g) Period (sec) 0.0 -0.5 20 25 30 35 40 PEER NGA Strong-Motion Database
• There are more than 100 variables describing source, path, and site conditions of a record • NGA-West has 6 distance measures, 4 site classes, V S30 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
Recorded Databases Simulation Databases Seismic Parameter Technical Basis Initial seismicity data, geotechnical Preliminary point source simulations Research to develop basis for range of inputs & development data, and crustal models undertaken (Initial parameter of alternate proponent models where appropriate (e.g., Q, Development collected estimates from TI team), Validations geometrical spreading, site response, stress drop, Kappa, slip by Working approaches for simulations distributions, rupture velocity, and appropriate correlations) determined Groups Recorded Databases Simulation Databases Parameter Community Distributions Content of seismicity catalogue Refinement of point source Distributions of parameters and their correlations SSHAC presented and discussed. Definition simulations & approach to finite fault developed through proponent-based discussions at of base rock and project crustal source simulations finalized workshops. Resulting “community distributions” Workshops models for simulations determined incorporating community input from developed that reflect the center, body and range of the through workshop input. workshops informed technical community. 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). Simulations Simulation sets used by simulation teams and specified based on Parameter Community Distributions. (see Figure 3) GMPE Input Database Review GMPE Approaches for RFPs Defined SSHAC Simulation and Seismicity Databases reviewed and sets of data for Sets of approaches to be included in RFP determined based on GMPE development selected. RFPs for GMPE teams will specify data input (e.g., data set, functional form, and magnitude scaling Workshops to be used in the development of various community models. constraints) developed during workshops in order to appropriately capture epistemic uncertainty. (see figure 4) GMPE GMPE Suite Developed Development Teams will participate in interactive GMPE developer workshops leading to a suite of community GMPEs GMPE Review GMPE Suite and Guidance Finalized & Finalization & Suite of GMPEs will be evaluated, including an assessment using the Scherbaum tool Site Response Final GMPE suite and logic tree weights chosen Guidance Guidance and documentation developed Vertical Motions Development Figure 1: Conceptual Approach for NGA-East Rock GMPE Development
• 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 Project Participants
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