Multi-method observation and analysis of a tsunami caused by glacier calving

Abstract

Abstract. Glacier calving can cause violent tsunami waves which, upon landfall, can cause severe destruction. Here we present data acquired during a calving event from Eqip Sermia, an ocean-terminating glacier in west Greenland. During an exceptionally well-documented event, the collapse of 9 × 10 5 m 3 ice from a 200 m high ice cliff caused a tsunami wave of 50 m height, traveling at a speed of 25-33 m s −1 . This wave was filmed from a tour boat at 800 m distance from the calving face, and simultaneously measured with a terrestrial radar interferometer and a tide gauge. Tsunami wave run-up height on the steep opposite shore at a distance of 4 km was 10-15 m, destroying infrastructure and eroding old vegetation. These observations indicate that such high tsunami waves are a recent phenomenon in the history of this glacier. Analysis of the data shows that only moderately bigger tsunami waves are to be expected in the future, even under rather extreme scenarios.

New fjords, new coasts, new landscapes: The geomorphology of paraglacial coasts formed after recent glacier retreat in Brepollen (Hornsund, southern Svalbard)

“…Similar observations were made along the coasts of Greenland, where rapid retreat of glaciers not only exposed new lands but also released significant amounts of sediment, leading to progradation of delta systems (Bendixen et al, 2017). Calving of Greenlandic glaciers can also produce extreme waves, over 10 m high, that are powerful enough to erode glacial landforms or beaches (Nielsen, 1992;Lüthi and Vieli, 2016). This can lead to substantial degradation of paraglacial coastal landscapes.…”

Ice-cliff failure via retrogressive slumping

“…4; see methods in the Data Repository). The 200-m-high ice front of Eqip Sermia in west Greenland is not vertical but slopes notably (~48°) (Engell, 2014;Lüthi and Vieli, 2016). Repeated subaerial slumping failure within its narrow fjord (~4 km) indicates that the ice is too weak to support 200 m cliffs.…”

Large-scale experiments into the tsunamigenic potential of different iceberg calving mechanisms

“…This type of waves, called iceberg-tsunamis hereafter (short for iceberg-generated tsunamis), is the focus of this work. Iceberg-tsunamis are typically observed in the summer season at grounded glaciers such as Helheim 5 and Eqip Sermia 15 and also for mountain glaciers including the Tasman Glacier 16 . Their relevance as a natural hazard and to stimulate additional iceberg calving has been highlighted in several recent studies 6,14,17–20 .…”