Civil Engineering Reference
In-Depth Information
FIGURE 3.35
Settlement caused by lateral movement of a retaining wall during the Kobe earthquake on
January 17, 1995. The industrial building is supported by a pile foundation. The Higashi Kobe cable-stayed
bridge is visible in the upper right corner of the photograph. (
Photograph from the Great Hanshin Bridge
Collection, EERC, University of California, Berkeley.
)
3.4.4 Flow Slides
Liquefaction can also cause lateral movement of slopes and create flow slides (Ishihara
1993). Seed (1970) states:
If liquefaction occurs in or under a sloping soil mass, the entire mass will flow or translate
laterally to the unsupported side in a phenomenon termed a flow slide. Such slides also develop
in loose, saturated, cohesionless materials during earthquakes and are reported at Chile (1960),
Alaska (1964), and Niigata (1964).
A classic example of a flow slide was the failure of the Lower San Fernando Dam caused
by the San Fernando earthquake, also known as the Sylmar earthquake. Particulars concern-
ing this earthquake are as follows (Southern California Earthquake Data Center 2000):
●
Date of earthquake: February 9, 1971
●
Moment magnitude
M
w
of 6.6
●
Depth: 8.4 km
●
Type of faulting: Thrust fault
●
Faults involved: Primarily the San Fernando fault zone
●
Surface rupture: A zone of thrust faulting broke the ground surface in the Sylmar-San
Fernando area (northeast of Los Angeles, California). The total surface rupture was
roughly 19 km (12 mi) long. The maximum slip was up to 2 m (6 ft).
