RAPID: Reconnaissance of Twin Landslides and Tsunami of 17 June 2017 in Greenland

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

A 17 June 2017 landslide-generated tsunami impacted a large fjord system in the northern part of western Greenland. This Grants for Rapid Response Research (RAPID) award supports the US participation in the reconnaissance survey of the twin landslides and tsunami. The team will coordinate the reconnaissance activities with the Government of Greenland, and follow protocols of the Geotechnical Extreme Events Reconnaissance (GEER) and the International Tsunami Survey Team (UNESCO). This event represents a unique research opportunity since two adjacent landslides were active with different outcomes. The eastern of the two landslides plunged 1 km into the Karrat Fjord and generated a tsunami in the Uummannaq fjord system. The landslide-generated tsunami washed 4 victims and several houses into the fjord at Nuugaatsiaq, about 30 km from the landslide. Eyewitnesses at Nuugaatsiaq and Illorsuit recorded the tsunami inundation on video. The active western landslide features a back scarp and large cracks, and therefore remains a hazard in Karrat Fjord, and has led to extended evacuations of a few native villages. The reconnaissance survey team supported on this award will collect high quality oblique aerial photogrammetry (OAP) of the landslide, scarp, and debris avalanche track as well as ground based tsunami inundation measurements in Karrat Fjord. The field observations will allow the research community to infer the predictive capability of different landslide and tsunami models. Tsunami eyewitness videos will be calibrated in situ to extract time series of flow depth and velocity. The obtained field data will be analyzed closely with the existing laboratory landslide tsunami data collected by past experimental projects. The primary project deliverable will be a comprehensive multi-scale, geo-referenced database of landslide parameters, tsunami damage, and flood zone characteristics combined with numerical model results. Education and outreach lectures and briefings will be given at native villages surveyed and to eyewitnesses interviewed. The Greenland landslide-generated tsunami highlights coastal hazards to communities not commonly exposed to earthquake generated tsunamis. Post disaster reconnaissance following major natural and man-induced events has yielded significant new insights into both the characteristics of the events and the performance of natural and man-made infrastructure subjected to these catastrophic events. The benefits of conducting these well-coordinated, well-executed landslide source and tsunami reconnaissance activities include early collection of perishable data and the establishment of multi-factor databases of information that form the basis for detailed long-term follow-on and mostly modeling based investigations. Through this study, researchers may be able to understand the unusual death toll of 4 people in the Arctic within days of the summer solstice. This event represents a unique opportunity as one landslide plunged into Karrat Fjord, while another neighboring one remains an active hazard. This will lead to post disaster observations of one landslide generated tsunami and potentially before disaster baseline data of a second one. Both landslide volumes will be estimated with oblique aerial photogrammetry (OAP). The spreading of the debris avalanche volume down the "Sturzbahn" will provide a landslide benchmark in comparison with the granular landslide spreading in physical models. The tsunami sources and magnitudes of historic tsunamis will be revisited in light of recent landslide and glaciological events. Collecting high quality inundation measurements will allow the community to infer the predictive capability of different models and evaluate their potential uses for inundation mapping and operational forecasts. Datasets and analytical tools generated by this research will be made available on the NSF-supported NHERI DesignSafe-CI.org web portal. This study will provide important information to local authorities as they are considering landslide monitoring and tsunami warning systems or permanent relocation of the evacuated villages. It will also provide a significant international experience for the U.S. students involved in the reconnaissance.