Numerical Modeling of the June 17, 2017 Landslide and Tsunami Events in Karrat Fjord, West Greenland

Heinrich

et al. 2019

Pure Appl. Geophys.

Self Cite

On the evening of December 22, 2018, the coasts of the Sunda Strait, Indonesia, were hit by a tsunami generated by the collapse of a part of the Anak Krakatau volcano. Hundreds of people were killed, thousands were injured and displaced. This paper presents a preliminary modeling of the volcano flank collapse and the tsunami generated based on the results of a 2D depth-averaged coupled model involving a granular rheology and a Coulomb friction for the slide description and dispersive effects for the water flow part.With a reconstructed total volume (subaerial and submarine) of the landslide of 150 million m 3 inferred from pre and post-collapse satellite and aerial images, the comparison of the simulated water waves with the observations (tide gauges located all around the strait, photographs and field surveys) is satisfactory. Due to the lack of information for the submarine part of the landslide, 2 Alexandre Paris et al. the reconstructed submarine slope is assumed to be approximately constant. A significant time delay on the results and particularly in the Bandar Lampung Bay could be attributed to imprecisions of bathymetric data. The sensitivity to the basal friction and to dispersive effects is analyzed through numerical tests. Results show that the influence of the basal friction angle on the simulated wave heights decreases with distance and that a value of 2°gives consistent results with the observations. The dispersive effects are assessed by comparing water waves simulated by a shallow water model and a Boussinesq model. Simulations with frequency dispersion produce longer wave periods and smaller wave amplitudes in the Sunda Strait and particularly in deep waters.

Section: Until Now One Of the Deadliest Recent Landslide Tsunamis Ismentioning

confidence: 99%

“…As in Paris et al (2019), tsunami generation is modeled by solving shallow water equations (Equations (4), (5) and (6)) during 80 seconds after the landslide triggering. Beyond 80 seconds, Boussinesq equations (Equations (7), (8) and (9)) are solved in order to take into account any possible dispersive effects during the propagation.…”

Section: Tsunami Modelmentioning

confidence: 99%

The December 22, 2018 Anak Krakatau, Indonesia, Landslide and Tsunami: Preliminary Modeling Results

Heinrich

et al. 2019

Pure Appl. Geophys.

Self Cite

“…As our UAV was not allowed to enter the no-fly zone above the settlement centre, we took oblique images from the recommended distance. Information about landslide genesis and some of the tsunami wave characteristics were extracted from remote-sensing analyses produced by USGS (Bessette-Kirton et al, 2017) and the collection of 60 geophysical reports published soon after the event (Clinton et al, 2017;Chao et al, 2017;Gauthier et al, 2018;Butler, 2019;Poli, 2017;Paris et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

“…90 m at the landslide site, and up to 50 m on the opposite side of the Karrat Fjord. Numerical modelling of the landslide and wave performed by Paris et al (2019) indicates that https://doi.org/10.5194/nhess-2019-376 Preprint. Discussion started: 2 January 2020 c Author(s) 2020.…”

Section: Landslide and Tsunami Characteristicsmentioning

confidence: 99%

Tsunamis unleashed by rapidly warming Arctic degrade coastal landscapes and communities – case study of Nuugaatsiaq, western Greenland

Jaskólski

2020

Preprint

Abstract. On the 17th of June 2017, a massive landslide which mobilized ca. 35–58 million m3 of material entered the Karrat Fjord in western Greenland. It triggered a tsunami wave with a runup height exceeding 90 m close to the landslide, ca. 50 m on the opposite shore of the fjord. The tsunami travelled ca. 32 km across the fjord and reached the settlement of Nuugaatsiaq with ca. 1–1.5 m high waves, which were powerful enough to destroy the community infrastructure, impact fragile coastal tundra landscape, and unfortunately, injure several inhabitants and cause 4 deaths. Here we report the results of the field survey of the surroundings of the settlement focused on the perseverance of infrastructure and landscape damages caused by the tsunami, carried out 25 months after the event.

“…The 2017 landslide in Karrat Fjord was described at a reconnaissance level of detail by Bessette-Kirton et al (2017) and Gauthier et al (2018), and subsequent minor landslide activity at the site was described by Svennevig et al (2019). The landslide triggered a tsunami that caused four fatalities in the nearby village of Nuugaatsiaq (Paris et al 2019). Additionally, Kelly (1980) described a pre-historic rock avalanche deposit 25 km north-east of Sisimiut at Aqqutikitsoq mountain, and speculated that it occurred in the 16th or 17th century based on, among other things, the deposits relation to a local Little Ice Age moraine.…”

Section: Existing Recordsmentioning

confidence: 99%

Preliminary landslide mapping in Greenland

Svennevig

2019

GEUS Bulletin

The landslide of 17 June 2017 in Karrat Fjord, central West Greenland, highlighted the need for a better understanding of landslides and landslide-generated tsunamis in Greenland and motivated a landslide screening project in 2018, led by the Geological Survey of Denmark and Greenland (GEUS; see also Svennevig et al. this volume). A central part of this project was to conduct a preliminary mapping of Quaternary and historical landslides in Greenland-the first effort of its kind. The main objective was to establish a landslide inventory database that can be used to identify areas prone to landslides and serve as a tool for gaining a better understanding of where, when and why catastrophic landslides take place in Greenland. This paper describes the workflow used to produce the preliminary landslide inventory of Greenland and discusses some of the initial results. To date (June 2019), I have mapped 564 landslides with the vast majority situated in the Nuussuaq Basin between Sigguup Nunaa (Svartenhuk Halvø), and Qeqertarsuaq (Disko) in West Greenland (Fig. 1). The inventory mapping is mainly based on observations and analyses of remotely sensed imagery and pre-existing geological maps. The mapping coverage was not systematic for all of Greenland, but focused on postglacial, potentially tsunamigenic landslides in inhabited coastal regions, i.e. on relatively large landslides on coastal slopes, mainly in West Greenland and small areas of East Greenland. However, smaller and inland landslides were included when they were encountered. Similarly, the less inhabited parts of Greenland were provisionally screened, but call for more thorough, systematic mapping in the future.