LARGE-SCALE EXPERIMENTS OF TSUNAMIS GENERATED BY ICEBERG CALVING

Abstract

Iceberg calving at outlet glaciers contributes to global sea-level rise in the context of climate change. This study investigates tsunamis generated by iceberg calving, so-called iceberg-tsunamis. Such tsunamis reached amplitudes of 50 m in the recent past and endanger human beings and coastal infrastructure. 66 unique large scale experiments have been conducted in a 50 m × 50 m large basin. These experiments involved the five iceberg calving mechanisms: A: capsizing, B: gravity-dominated fall, C: buoyancy-dominated fall, D: gravity dominated overturning and E: buoyancy-dominated overturning. Gravity-dominated icebergs essentially fall into the water body whereas buoyancy-dominated icebergs essentially rise to the water surface. The icebergtsunamis from gravity-dominated mechanisms (B and D) are roughly an order of magnitude larger than from mechanisms A, C and E. The maximum wave heights and their decay with distance from the calving locations are correlated with six dimensionless parameters, where the Froude number, the relative iceberg width and the relative released energy were identified as the most important ones. Empirical equations for initial iceberg tsunami hazard assessment for the five iceberg-calving mechanisms individually and all mechanisms combined were derived predicting the wave heights reasonably well. Ongoing and future work aims to analyse the wave parameters in further detail, compare iceberg- with landslide-tsunamis and investigate iceberg-tsunamis numerically.