Dune Morphology as an Indicator of Paleotsunamis

Analysis of modern and past tsunamigenic features from within New Zealand and around the world have identified a suite of tsunami-related geomorphological features in dune systems including; Pedestals — remnant sections of dune ridge separated by scoured areas; Hummocky topography/Sand sheets — formed landward from pedestals (hummocky topography is the old, weathered equivalent of sand sheets); Parabolic dune fields — remobilised sand sheets landward of pedestals; Low Profile Sequences — post-tsunami feature indicative of changes to coastal sediment budget. The type of features formed by a tsunami, and the ability to detect and interpret tsunami geomorphology by LIDAR (and also in the field) hinges on the interactions between five key criteria; the availability and type of sediment (e.g. sand/gravel); embayment type; aprograding or eroding coast; small or large accumulation space; and whether there is a wet or dry landward environment.