Major Projects &
Seismic Hazard and Risk Analysis (SHRA)
The purpose of this activity is to apply SCEC knowledge to the development of useful and useable information and techniques related to earthquake hazard and risk in California. Such information and techniques may include improved representations of seismic hazards, in some cases in terms of new scalar or vector ground motion intensity measures; representations of seismic hazards using ground motion time histories that are also validated for risk analysis applications; rupture-to-rafters simulations that integrate the physics-based generation of ground motion, its propagation through the earth, and its interactions with the built environment; and improved site/facility-specific and portfolio/regional risk analysis (or loss estimation) techniques and tools. Projects that involve interactions between SCEC scientists and members of the community involved in earthquake engineering research and practice are especially encouraged. While supported from the same funds used for other SCEC activities, projects in this activity will often be linked to the Ground Motion Prediction and to special projects. These projects include the CEA Project, the Extreme Ground Motion Project, the NGA-H Project, the NSF LA Tall Buildings Project, and the Tall Buildings Initiative; these projects illustrate the kinds of work that are relevant to SHRA. In the following, the Special Projects are described and related to the various SCEC3 Priority Science Objectives.
The current California Earthquake Authority Project contains activities related to the development of a uniform earthquake forecast for the whole of California (A1, A2), the NGA-H Project discussed below (B1, B3, B4), and rupture-to-rafters simulations involving woodframe buildings (B6). Plans to continue this project in 2008 have not yet been developed.
The Extreme Ground Motion Project supports SCEC research on evaluation and validation of existing rupture dynamics models for ground motion simulation (B1); enhancement of rupture dynamics models to include more physics (B1); the use of these dynamic models, together with kinematic ground motion modeling, to simulate ground motions (B); and analyses of nonlinear wave propagation and site response (B5), for the purpose of understanding the generation of and potentially identifying bounds on extreme ground motions within the context of the Yucca Mountain Repository (B2). This project will continue in 2009 and beyond.
The planned NGA-H Project will involve the use of broadband strong motion simulation to generate ground motion time histories for use, in conjunction with recorded ground motions, in the development of ground motion attenuation relations for hard rock that are based on improved sampling of magnitude and distance and improved understanding of the relationship between earthquake source and strong ground motion characteristics (B1, B3, B4, B5). Of particular interest is that the NGA-E (empirical) relations are noticeably lower than earlier ground-motion attenuation relations. Are the current SCEC broad-band simulations consistent with the NGA-E findings? Broadband simulation methods are verified (by comparison of simple test case results with other methods) and validated (against recorded strong ground motions) before being used to generate broadband ground motions for use in model development. These simulation activities for verification, validation, and application are done on the SCEC Broadband Simulation Platform, which is currently under development.
The pending NSF LA Tall Buildings Project will involve enhancement of simulations of long period ground motions in the Los Angeles region that have been generated by TeraShake and CyberShake, using refinements in source characterization and seismic velocity models (B1, B4), and evaluation of the impacts of these ground motions on tall buildings (B6). It will also involve the development of methods for evaluating and characterizing the potential of faults to generate buried faulting as well as surface faulting earthquakes (A), and evaluating differences in seismic demands imposed by these two categories of earthquakes (B6).
The current Tall Buildings Initiative involves the simulation of ground motion time histories of large earthquakes in Los Angeles and San Francisco for use by practicing engineers in the design of tall buildings (B), and the development and application of procedures for selecting and scaling ground motion time histories for use in representing design ground motions (B6). As is the case in all of the Special Projects described above, validation of the earthquake simulations (B4) for use in seismic hazard and/or risk analysis is an important step that calls for collaboration between earthquake scientists and engineers.
Proposals for other innovative projects that would further implement SCEC information and techniques in seismic hazard and risk analysis, and ultimately loss mitigation, are encouraged.
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