Seismic signals in coastal dune systems

Abstract

Coastal dune ridge systems throughout the world form initially in response to phases of abundant sand supply, and yet researchers rarely consider the importance of seismic-related activity to dune formation or destruction. New Zealand examples of seismic-related coastal dune formation and their occasional remobilisation are discussed. Pulses of sand sized sediment produced by large earthquakes, and transported to the coast by geomorphic processes, can generate new dune ridges. Tsunami inundation can modify existing dunes producing features such as relict dune pedestals, landward sand sheets, hummocky topography, and parabolic dunes. The case is put forward for the need to consider evidence for catastrophic events in coastal dune systems, particularly when working in tectonically active areas of the World. Recognition of some of the effects of seismic-related processes on coastal dunes however does not mean that these are easily identified in the field, or even present in the existing landscape. It does however mean that they should not be ignored.