Rebekka Steffen, Holger Steffen, Robert Weiss, Benoit S. Lecavalier, Glenn A. Milne, Sarah A. Woodroffe, Ole Bennike

Due to their large mass, ice sheets induce significant stresses in the Earth’s crust. Stress release during deglaciation can trigger large-magnitude earthquakes, as indicated by surface faults in northern Europe. Although glacially-induced stresses have been analyzed in northern Europe, they have not yet been analyzed for Greenland. We know that the Greenland Ice Sheet experienced a large melting period in the early Holocene, and so here, we analyze glacially-induced stresses during deglaciation for Greenland for the first time. Instability occurs in southern Greenland, where we use a combined analysis of past sea level indicators and a model of glacially-triggered fault reactivation to show that deglaciation of the Greenland Ice Sheet may have caused a large magnitude earthquake around 10,600 years ago offshore south-western Greenland. The earthquake may have shifted relative sea level observations by several meters. If the earthquake-induced stress release was created during a single event, it could have produced a tsunami in the North Atlantic Ocean with runup heights of up to 5 m in the British Isles and up to 7.5 m along Canadian coasts.