The first primary earthquake hazard, surface rupture, can be caused by vertical or horizontal displacement on either side of a ruptured fault, which can affect enormous areas of land (tectonic movement).
When the focus of the earthquake is shallow, a fault rupture may break through to the Earth’s surface, deforming the ground and producing deep ruts, steep banks and lateral displacements. These ground deformations can cause severe damage to structures, roads, railways and buried infrastructure, such as pipelines.
Surface fault ruptures have been known to deviate around more substantial structures due to the strength of the foundation and localised compression of the soil. However this is not always the case. A surface rupture that intersects with a lightweight structure almost always causes severe damage, often tearing smaller buildings apart.