Research Aligns Numerical Simulations with Geological Evidence to Find Tsunamis Can Impact Small Inland Lakes
Using a multidisciplinary approach combining geological analysis and advanced numerical modeling, researchers from Khalifa University and the University of Savoy Mont Blanc have uncovered evidence of a previously unreported 12,000-year-old palaeo-tsunami event in Lake Aiguebelette, an alpine lake in France.
Since this tsunami was caused by an instability of underwater sediments in relation to a past earthquake, the study in particular shows that tsunami waves can happen even in small lakes, and that a major rock collapse is not always necessary to trigger such an event.
The findings, in the Journal of Geophysical Research – Solid Earth (Wiley), titled 鈥楴umerical Reconstruction of Landslide Paleotsunami using Geological Records in Alpine Lake Aiguebelette鈥� detail the reconstruction of this ancient tsunami event and challenge conventional assumptions about the causes and behavior of tsunamis. The research team includes Dr. Denys Dutykh, Associate Professor, Mathematics, Khalifa University; Muhammad Naveed Zafar, PhD Researcher, and Dr. Pierre Sabatier, Lecturer, Earth Sciences, University of Savoy.聽
The team’s numerical simulations, which closely matched the available geological data, revealed that the palaeo-tsunami took place approximately 11,700 years ago, enabling the detection of traces of the event in deep sedimentary layers. A mathematical modeling of the paleo underwater landslide, which indicates a significant paleo-tsunami event, also provided valuable insights into the risks of landslide-induced tsunamis in mountainous regions.
By aligning computer simulations with the actual geological evidence, the researchers determined that wave dispersion played a relatively minor role in this particular lacustrine (lake-based) tsunami event, highlighting how tsunamis can also occur and impact small inland bodies of water.
Several advanced techniques were used to study the lake and gather data about the event, including identifying the initial area where the event originated. By acquiring highly detailed bathymetric data, which provided very accurate measurements of the lake’s depth, they also used seismic profiling and core sediment to create and characterize the mass wasting deposit in the lake sediment. Building on this geological fieldwork data, researchers conducted complex computer modeling and simulations. Mathematical models were used to simulate the underwater landslide and the resulting tsunami. The depth-averaged visco-plastic Herschel-Bulkley rheological model, known as BingClaw, was employed for the landslide simulation. For the tsunami, both the depth-averaged nonlinear shallow water equations (NSWE) model, GeoClaw, and the dispersive tsunami model, BoussClaw, were utilized.聽
Dr. Denys Dutykh said: “Researching palaeo-tsunamis is crucial due to the long recurrence intervals of these events. This multidisciplinary research not only enhances our understanding of tsunamis in small lacustrine settings, but also lays the groundwork for future investigations in other lakes and coastal areas. The contribution of both mathematicians and the geologists were crucial. Without the successful reconstruction of the event using geological and numerical studies, this work would not have been accepted for publication in such a prestigious journal.”聽
The team plans to expand their studies to additional lakes and conduct onshore tsunami deposit surveys at Lake Aiguebelette to further refine their understanding of this ancient palaeo-tsunami event.
Alisha Roy
Science Writer
4 June 2024
