Propagation of the Storegga tsunami in the south eastern North Sea

Numerical simulations of the 8150 BP Storegga slide event in the Norwegian Sea need to be consistent both with landslide runout and with observations of tsunami run-up. Here we focus on the southern North Sea, South East of Dogger Bank, and the shores of Denmark and Germany. The slide volume and dynamics need to generate a realistic initial tsunami wave and the simulation of the propagation and inundation of the tsunami would need the correct bathymetry of the North Sea 8150 years ago. From both Denmark and Germany there have been reports of deposits claimed to be associated with the Storegga tsunami. We simulate the slide using a recent cohesive landslide model, that has demonstrated success in predicting both the extent of runout deposits and tsunami run-up heights farther north, and we run suites of tsunami simulations to predict tsunami surface elevations, velocities, and arrival times. Appreciating the uncertainty associated with the paleobathymetry, we parametrize a continuum of bathymetric models between the present day topobathymetry and two different paleobathymetric models and perform simulations for multiple candidate bathymetric models. For many models in which Dogger Bank is completely submerged, the shallow water in this part of the North Sea still represents a significant barrier to the tsunami propagation. We compare tsunami metrics between the alternative topobathymetries systematically and conclude that the tsunami surface elevations and velocities in the southeastern North Sea are probably too small to have caused erosion and significant deposition of tsunami debris along the coasts of Denmark and Germany. All numerical simulation results performed for this study are openly archived on the Geo-INQUIRE Simulation Data Lake.

We acknowledge Geo-INQUIRE, funded by the European Commission under project number 101058518 within the HORIZON-INFRA-2021-SERV-01 call, DT-GEO, funded by Horizon Europe under Grant Agreement No 101058129, and ChEESE-2P, funded by the European Union and the European High Performance Computing Joint Undertaking (JU) together with Spain, Italy, Iceland, Germany, Norway, France, Finland, and Croatia under grant agreement No 101093038.