Geology Reference
In-Depth Information
Class
Condition
Details and examples
1. Stable
Acceleration less than that
necessary to cause permanent
displacement
2. Permanent
displacement
but stable
FoS post-quake > 1.0
Damage may allow deterioration
and later collapse
Tension cracks resulting from Erzincan earth-
quake, Turkey, 1992
3. Failure
Metastable condition so that
acceleration leads to cata-
strophic failure directly
Reducing shear strength so that
FoS is less than 1.0 after earth-
quake shaking has
finished.
Deteriorating condition follow-
ing earthquake
e.g. Tsao ling reactivated landslide, Chi Chi earth-
quake, Taiwan, 1999
Rise in water pressure due to
collapse of soil structure or
regional changes in hydrogeolo-
gical conditions
Rockfalls and other landslides may continue for
days after an earthquake
