Lateral spreading: Evidence and interpretation from the 2010-2011 Christchurch earthquakes

In the 2010-2011 Canterbury earthquakes widespread liquefaction occurred over nearly half of the urban area of Christchurch. The most severe damage to buildings and infrastructure was often associated with lateral spreading and consequent large ground distortion and permanent ground displacements. This paper presents analysis, results and interpretation of lateral spreads using measurements from detailed ground surveying at a large number of locations along the Avon River. Classification of lateral spreads based on the magnitude and spatial distribution of permanent ground displacements is first presented, and then key characteristics of soil layers and ground conditions associated with different classes of lateral spreads are identified and discussed. Evidence of both global effects from topographic features and local effects related to density, thickness and continuity of critical layers is presented highlighting the need for a systematic approach in the engineering evaluation of lateral spreading in which particular attention is given to key factors governing lateral spreading.