(a) Surface faulting

An earthquake fault is a geological feature associated with the generation of earthquakes. It is the displacement that reaches the earth\’s surface during slip along a fault. As seen in El Asnam Earthquake of 10 October, 1980, surface faulting may extend more than 30km. Typical damage that may occur due to surface faulting include: overturning of trains due to bending of railroad tracks, damage to irrigation channels or rupture of water and sewage lines that crossed the fault rupture (Quake Centre, 2014).

(b) Ground cracking

Ground cracking is possible when the soil at the surface loses its support and sinks, or when it is transported to a different location. It occurs because, when displaced, a soil layer breaks causing fissures, scarps, horsts and grabens on the ground surface (Quake Centre, 2014).

(Reproduced from Images Courtesy of Umut Akguzel)

(c) Ground subsidence

Ground subsidence is a phenomenon in which the ground surface of a site settles or depresses as a result of compaction induced by an earthquake’s vibrations. Sites with loose or compressible soils are the most likely to experience ground subsidence. Un-compacted fills or reclaimed lands are in this category.
As it involves a relatively uniform soil deformation, ground subsidence usually causes only minor damages to structures. This damage may be in the form of cracks and perhaps some tilting of the building.
In contrast, it may substantially damage elongated structures such as pipelines, channels, and road embankments (Quake Centre, 2014).

(d) Landslides

Landslides can be triggered by strong earthquakes. These landslides represent the failure of slopes that are marginally stable before the earthquake and become unstable as a result of the violent shaking generated by the earthquake.
A structure may be damaged by a landslide if the structure, or part of it, happens to be on top of the soil mass that comes down during the landslide.
For the most part, earthquake induced landslides are small, so the damage they induce is usually localized. However, there have been some instances in which landslides have buried entire towns and villages (Quake Centre, 2014).

(Reproduced from Rebuild Christchurch)

(e) Soil liquefaction

Soil liquefaction is a phenomenon by which fine saturated granular soils temporarily change from a solid to a liquid state and as a result lose their ability to carry loads or remain stable.
It occurs when a loose soil is vigorously shaken or vibrated, and thus it is commonly observed during earthquakes.

It is caused by water pressure build-up that is generated when saturated soil is compacted by the effect of the earthquake vibrations. As a result of this water build-up, an upward water flow is generated and the soil particles float in the water.

(Reproduced from Images Courtesy of Umut Akguze)

Soil liquefaction is one of the most dramatic causes of earthquake damage and has been responsible for a substantial amount of damage in previous earthquakes. Tilting and settlement of apartment buildings caused by soil liquefaction following the 1999 earthquake in Kocaeli, Turkey, are seen in this image (Quake Centre, 2014).

(Reproduced from US Geological Survey)