Potential for timing high-energy marine inundation events in the recent geological past through age-dating of reef boulders in Fiji

James P Terry,Samuel Etienne

doi:10.1186/s40562-014-0014-8

Abstract

Transported coastal boulders have increasingly come to represent a valuable element of investigations within the broader framework of multi-proxy approaches applied to coastal hazard studies. Through a case study on Taveuni Island in Fiji, this paper outlines some approaches and hindrances to effective timing of prehistorical high-energy marine inundation events (storms and tsunamis) on tropical coastlines from the evidence of reef-platform carbonate boulders. Various sources of errors are outlined that investigators must consider when attempting to use carbonate boulder ages as a surrogate for timing past events. On Taveuni, uranium : thorium dates with a high level of precision (1–7 years) suggest that major inundation events have a return period of approximately 40–45 years since 1650 AD. Of particular importance, considerably different age dates are provided by coral samples sourced from the top and bottom (i.e. opposite faces) of individual boulders, so highlighting interpretation biases that must be avoided.

Highlights

Boulder analysis for interpreting coastal hazards In recent years the study of high‐energy marine inundation (HEMI) events on tropical coastlines has become increasingly popular as researchers try to develop a better understanding of the frequency of coastal hazards [1,2]
If we are willing to accept that the youngest of each pair of dates obtained for individual Reef-platform carbonate boulder (RPCB) indicates the approximate timing of the HEMI events that produced the boulders, it is helpful to plot the data on a timeline in order to visualise the relative frequency and magnitude of the events (Figure 4)
The timing and frequency of HEMI events through the Holocene has been achieved for tropical coastlines in Queensland, Australia [38,39], the Netherlands Antilles in the Caribbean [9] and for islands in the South China Sea [19,40]

Summary

Introduction

Boulder analysis for interpreting coastal hazards In recent years the study of high‐energy marine inundation (HEMI) events on tropical coastlines has become increasingly popular as researchers try to develop a better understanding of the frequency of coastal hazards [1,2]. In part, this is the result of both public and scientific attention being brought into sharper focus by tragic events such as the 2004 Indian Ocean and 2011 Tōhoku-oki tsunamis, as well as the annual litany of severe tropical cyclones and typhoons.

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Discussion

Conclusion