1. Southern California Earthquake Center SCEC Technical Activity Groups (TAGs) Self-organized to develop and test critical methodologies for solving specific types of forward and inverse problems Successful groups share a modus operandi: –posing of well-defined “standard problems” –solution of these problems by different researchers using different algorithms or codes –a common cyberspace for comparing solutions –meetings to discuss discrepancies and potential improvements

2. Southern California Earthquake Center SCEC Technical Activity Groups (TAGs) Rupture Dynamics Code Verification Source Inversion Verification Earthquake Simulators Geodetic Detectors Ground Motion Simulation Validation

3. Southern California Earthquake Center Validation vs. Verification Verification substantiates that a model “does what it is supposed to do” at a specified level of precision; e. g., the mathematics is correct and properly implemented, say, in a computer code. Validation establishes that a model adequately describes the behavior of real systems within its proposed domain of applicability and that its epistemic uncertainties are properly characterized. Verification can be accomplished by comparison with other models (e.g., through cross-validation), but validation requires the comparison of model results with observations.

4. Southern California Earthquake Center Ground Motion Simulation Validation TAG What criteria should be imposed on SCEC ground motion simulations to qualify them for earthquake engineering applications? –Which engineering applications? –Which ground motion simulations? Broadband platform CyberShake platform How should the activities of this TAG be coordinated internally within SCEC and externally with engineering partnerships (e.g., PEER)?