Civil Engineering Reference
In-Depth Information
Figure 1.24
Fault rupture observed on northern Awaji Island during the 1995 Kobe (Japan) earthquake: aerial
view with the fault rupture that cuts across the middle of the picture (
left
) and close-up showing both vertical and
horizontal offset of the Nojima fault (
right
) (
courtesy of
Geo-Engineering Earthquake Reconnaissance, University
of Southern California, Los Angeles)
Figure 1.25
Effects of ground settlements and uplift during the 1999 Kocaeli (Turkey) earthquake: fl ooding (
left
)
and artifi cial waterfalls (
right
)
several approach structures and abutments of bridges was observed in the San Fernando (1971), Loma
Prieta (1989), Northridge (1994) and Kobe (1995) earthquakes. Settlement, tilting and sinking of build-
ings have been observed in the aftermath of several earthquakes worldwide. Differential ground settle-
ments may cause structural distress. Granular soils are compacted by the ground shaking induced by
earthquakes, leading to subsidence. This type of ground movement affects dry, partially saturated and
saturated soils with high permeability. Subsidence of 6-7 m was observed during the New Madrid
earthquakes (1811-1812) in the Mississippi Valley in the USA. Subsidence of areas close to sea, lakes
and river banks may cause fl ooding of ports, streets and buildings. In some cases, artifi cial waterfalls
may also be generated by settlements and uplifts as shown in Figure 1.25, from the Kocaeli, Turkey,
earthquake of 1999.
(iii) Liquefaction
Excessive build -up of pore water pressure during earthquakes may lead to the loss of stiffness and
strength of soils. The excessive pore water pressure causes ejection of the soil through holes in the
ground, thus creating sand boils. Figure 1.26 shows two examples of liquefaction during the 1998
Adana-Ceyhan (Turkey) and the 2001 Bhuj (India) earthquakes. The ejection of soil causes loss of
