The sinking city: Earthquakes increase flood hazard in Christchurch, New Zealand

Abstract

Airborne light detection and ranging (LiDAR) data were acquired over the coastal city of Christchurch, New Zealand, prior to and throughout the 2010 to 2011 Canterbury Earthquake Sequence. Differencing of pre- and post-earthquake LiDAR data reveals land surface and waterway deformation due to seismic shaking and tectonic displacements above blind faults. Shaking caused floodplain subsidence in excess of 0.5 to 1 m along tidal stretches of the two main urban rivers, greatly enhancing the spatial extent and severity of inundation hazards posed by 100-year floods, storm surges, and sea-level rise. Additional shaking effects included river channel narrowing and shallowing, due primarily to lique..