Chiou and Youngs PEER-NGA Empirical Ground Motion Model for ...

the top of rupture located at x = 0 and the fault dipping downward towards positive x. Figure
16 show the variation of the factor [ 1−
RJB
/ RRUP]
with location along three lines for the case
when the top of rupture at x=0 is at the ground surface. Line 1 runs from negative values in
the foot wall to positive values in the hanging wall. In the foot wall, RJB = RRUP and the
hanging wall effect is zero. Thus the function acts as a switch equivalent to other
formulations that only apply the effect on the hanging wall side of the fault. Lines 2 and 3
show the variation of [ 1−
RJB
/ RRUP
] as one moves away from the rupture along strike. Line
2 is located near the top of the rupture and line 3 near the bottom. The function
[ 1−
RJB
/ RRUP
] decays much more rapidly for Line 2 than for Line 3. Most of Line 2 lies
outside of the area typically defined as subject to the hanging wall effect while much of Line
3 for small values of y lines within the hanging wall area. The term [ 1−
RJB
/ RRUP
] provides
for a smooth transition in the level of the hanging wall effect throughout the along strike
region.
y
40
30
20
10
0
-10
-20
-30
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100
1-Rjb/Rcld
1.2
1
0.8
0.6
0.4
0.2
x
Figure 15: Map view of example fault rupture.
0
-40 -20 0 20 40 60 80 100 120
x (line 1) or y (lines 2 and 3)
Line 1 (y=0)
Line 2 (x=3)
Line 3 (x=10)
Rupture
Figure 16: Variation of the term [ 1−
RJB
/ RRUP
] with location for the three lines shown on Figure
15. Top of rupture is at the ground surface at x=0.
Figure 17 shows the variation of the term [ 1−
RJB
/ RRUP
] for the case when the top of rupture
is located at a depth of 5 km. Now, the hanging wall effect extends into the footwall side of
C&Y2006 Page 24
Line 1
Line 2
Line 3