Environmental Engineering Reference
In-Depth Information
vertical or dipping faults, the direction of rupture propagation in the near field can cause
substantial differences in the level of shaking for different orientations relative to the
fault's strike. In the Kobe (1996) and Northridge (1994) events it was found that sites close
to the source experienced strike-normal peak velocities substantially larger than strike-
parallel velocities, particularly during periods longer than about 0.5 sec (Bray, 1995).
Displacement vs. Magnitude
Relationships between the maximum surface displacement for various types of faults
and earthquake magnitude based on recorded events world wide, as of 1977, is given in
Figure 11.26.
Wells and Coppersmith (1994) have proposed a relationship for the western United
States. The magnitude vs. the maximum displacement (MD) along a fault rupture length
for the western United States can be estimated (NRC, 1997) from the following:
M w
a
b log (MD)
(11.17)
where
strike-slip:
a
6.81m,
b
0.78m,
s
0.29
normal:
a
6.61m,
b
0.89m,
s
0.39
all:
a
6.69m,
b
0.74m,
s
0.40
with MD being the maximum displacement.
Feet
Meters
40.0
10.0
8.0
6.0
4.0
Limits of
world wide
historic data
20.0
10.0
8.0
6.0
4.0
San Fernando, 1971
2.0
Limits of
North America
data
1.0
0.8
0.6
0.4
2.0
1.0
0.8
0.6
0.4
0.2
0.1
0.08
0.06
Oroville, 1975
0.2
0.04
0.1
0.08
0.06
0.04
Additional data needed
to establish relationships
in this area
FIGURE 11.26
Relationship between maximum surface
displacement and earthquake magnitude
reported for historic events of surface faulting
throughout the world. (From Taylor, C.L. and
Cluff, L.S., Proceedings of ASCE, The Current
State of knowledge of Lifeline Earthquake
Engineering, Specialty Conference, University
of California, Los Angeles, 1977, pp. 338-353.
With permission.)
0.02
Imperial, 1966
0.01 3
4
5
6
7
8
9
Earthquake magnitude
Explanation
type of fault displacement
Reverse slip
Reverse oblique-slip
Strike slip
Normal slip
Normal oblique-slip
 
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