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Table 2.5. Source parameters ofsimulated event in parametric analyses
Fault area ( km 2
M
o (Nm)
)
L (km)
W (km)
Risetime(s)
Slip (m)
7 . 079 · 10 16
5.2
17.4582
5909.014
2954.51
0.49004
0.1141
Fig. 2.12. Outline ofvalley-fault configurations usedinsource simulations
To investigate the influence of different types of radiation from the source onto the
valley, a set of basin-fault configurations was chosen for the simulations. As shown in
Figure 2.12, the valley longitudinal axis was placed along the X and Y axes and along
thedirectionat45 ,eitherparallelorperpendiculartothem.Sincethecross-sectioncon-
sidered is non-symmetrical, some analyses involved the valley with both a “normal” and
a reversed shape. The hypocentral distance of thevalley centre isabout 20km.
It is worth noting that the computational code adopted introduces an intrinsic high freq-
uency cut-off at about 3Hz. Simulated displacement histories were at the end band-pass
filtered between 0.2Hz and 5Hz.
5% damped DRS were computed and then averaged over the valley zones defined in
Figure 2.11. Figure 2.13 shows the results for every zone, for the different fault mech-
anisms and configurations, but only the worst case average DRS at the surface are
shown. In each graph also the median
s.e. interval (shaded band) from the attenua-
tion relation (2.2) is displayed, for ground type C, together with the median
±
s.e. band
(unshaded) of the correction obtained from Choi et al. (2005) residuals, using model B2
for Southern California. The vertical lines indicate the fundamental (average) 1D period
for thezone considered.
+
 
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