Figure 1. Effect of smoothing on the empirical correlation matrix for horizontal
epsilons in perpendicular directions at two periods (T1 and
T2). (a) Before smoothing. (b) After smoothing.
Figure 2. Correlation coefficients for perpendicular horizontal epsilons at the same
period. Empirical results, the prediction from equation
(7), and the correlations implied
from the ratios of standard deviations in Boore et al.
(1997) and Spudich et
al. (1999).
Figure 3. Correlation coefficients between horizontal epsilons and vertical epsilons at
the same period. Empirical results and the prediction from equation
(8).
Figure 4. Correlation contours for horizontal epsilons in the same direction at two
periods (T1 and T2). (a) Smoothed
empirical results. (b) The prediction from equation
(9). (c) The prediction from
Abrahamson et al. (personal comm., 2003). (d) The prediction from Inoue and
Cornell (1990).
Figure 5. Correlation contours for vertical epsilons in the same direction at two
periods (T1 and T2). (a) Smoothed
empirical results. (b) The prediction from equation
(10).
Figure 6. Correlation contours for horizontal epsilons in perpendicular directions at
two periods (T1 and T2). (a) Smoothed
empirical results. (b) The prediction from equation
(11).
Figure 7. Correlation contours of vertical epsilons with horizontal epsilons at two
periods (T1 and T2). (a) Smoothed
empirical results. (b) The prediction from equation
(12).
Figure 9. Overlaid contours at four correlation levels for the empirical correlations,
the prediction from equation (9)
and the prediction from Abrahamson et al. (personal comm., 2003).
Figure 10. Contours of vector-valued probabilistic seismic-hazard analysis. The contours
denote the mean annual rate of exceeding both the
Saverticaland the Sahorizontal
values. P.E., Probability of exceedance.
Figure 11. Samples of 20 response spectra from magnitude 6.5 earthquakes with a
source-to-site distance of 8 km. The simulated spectra use means and variances
from Abrahamson and Silva (1997).
(a) Simulated spectra using correlation coefficients equal to zero between all
periods. (b) Simulated spectra using correlation coefficients equal to one
between all periods. (c) Simulated spectra using correlation coefficients from
equation (9). (d) Real spectra
from recorded ground motions with magnitude 6.5 and distance 8
km.