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Poster Abstracts
STOCHASTIC SIMULATION OF EARTHQUAKE GROUND MOTION COMPONENTS FOR SPECIFIED
EARTHQUAKE AND SITE CHARACTERISTICS: A TOOL FOR PERFORMANCE-BASED EARTHQUAKE
ENGINEERING (B-009)
S. Rezaeian
A method for generating an ensemble of orthogonal ground motion components for specified earthquake and site
characteristics is presented (Rezaeian and Der Kiureghian, 2011). The generated synthetic ground motions can be used in
performance-based earthquake engineering when a large number of recordings is required and real recorded motions are
scarce or lacking. The method employs a parameterized stochastic model that is based on a time-modulated filtered whitenoise
process with the filter having time-varying characteristics. Whereas the input white-noise excitation describes the
stochastic nature of the ground motion, the forms of the modulating function and the filter and their parameters characterize
the evolutionary intensity and nonstationary frequency content of the ground motion. The stochastic model is fitted to a
database of recorded horizontal ground motion component pairs that are rotated into their principal axes, a set of orthogonal
axes along which the components are statistically uncorrelated. Model parameters are identified for each ground motion
component in the database. Using these data, predictive equations are developed for the model parameters in terms of
earthquake and site characteristics: faulting mechanism, earthquake magnitude, source-to-site distance, and site conditions.
Furthermore, correlation coefficients between parameters of the two components are estimated. Given a design scenario
specified in terms of earthquake and site characteristics, the results of this study allow one to generate realizations of
correlated model parameters and use them along with simulated white-noise processes to generate synthetic pairs of
horizontal ground motion components along the principal axes. The proposed simulation method can be easily extended to
the vertical component. It does not require any seed recorded ground motion and therefore is ideal for use in performancebased
earthquake engineering. This simulation method has been validated by comparing the resulting synthetic motions with
real recorded motions and by comparing the statistics of their elastic response spectra with the values predicted by the Next
Generation Attenuation ground motion prediction equations.
Rezaeian and Der Kiureghian. Simulation of orthogonal horizontal ground motion components for specified earthquake and
site characteristics. Earthquake Engineering & Structural Dynamics, Published online (Early View): May 17, 2011. DOI:
10.1002/eqe.1132.
PARTIAL TESTS AND ACID TESTS OF GROUND-MOTION MODELS FOR INHIBITION OF VERY STRONG
SHAKING (B-015)
D.A. Rhoades, G.H. McVerry, and J.X. Zhao
Abrahamson and Wooden (2010) (AW) pointed out that the Rhoades et al. (2008) (RZM) test for inhibition of very strong
shaking in ground-motion models assumes independence of total residual; it does not allow for correlation in the total
residuals resulting from the inclusion of both inter-event and intra-event error terms in the models. Therefore, for a highly
unbalanced sample, such as that chosen for fitting the Abahamson and Silva Next Generation Attenuation (AS-NGA) models,
the test does not give a reliable estimate of the statistical significance of deviations of the expected number of exceedances of
very strong ground-motion levels from the actual number in the sample. AW proposed replacing the RZM test by two partial
tests, in which either the random inter-event or intra-event errors are regarded as fixed effects, and found that the AS-NGA
model passed these partial tests. This shows that the model can be confidently applied to future earthquakes where one of
these error terms is known exactly in advance, but does not show how the model can be expected to perform in the realistic
case where both of the error terms are random. Here, using a simulation approach, we adapt the RZM test to take account of
correlation in the total residuals, and apply it to test for inhibition in the Zhao et (2006) and AS-NGA models for peak ground
acceleration.
A TESTABLE EARTHQUAKE LIKELIHOOD MODEL BASED ON PROXIMITY TO KNOWN SOURCES (B-
121)
D.A. Rhoades and M.W. Stirling
Known earthquake sources include mapped faults and past earthquakes. We propose a long-term earthquake likelihood
model which makes use of both types of source, but does not invoke the concepts of fault segments or characteristic
earthquakes. The model has two components, one based on proximity to past earthquakes, taking into account the magnitude
of each, and another based on proximity to mapped faults, taking into account the slip-rate of each. The Gutenberg-Richter
law is invoked for earthquake magnitudes and an inverse power law for the diminution of earthquake rate density with
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