The interactions of tsunami and tides

• Main Author: Hill, Jon
• Format: Conference Object
• Language: unknown
• Published: figshare 2017
• Subjects: 40604 Natural Hazards; FOS Earth and related environmental sciences; Greenland; Norway; Storegga; Faroes
• Online Access: https://dx.doi.org/10.6084/m9.figshare.5373121.v1; https://figshare.com/articles/presentation/The_interactions_of_tsunami_and_tides/5373121/1

Talk given at 5th International Tsunami Conference. Numerical modelling of palaeotsunamis requires a cross-disciplinary approach incorporating new softwaredevelopment, sea-level change dynamics, tectonics, fluid dynamics, sedimentology and even archaeology. Thereis a huge potential for this field to make a significant contribution to tsunami hazard assessmentby recreating and understanding past events. The interaction of tides with past events is key to interpreting thesedimentary record they leave behind. Tidal dynamics affect past sea-level reconstructions, as well as themaximum wave estimates from the sedimentary record. Here, the first reconstruction of the Storegga tsunami thatincorporates the effects of the tidal dynamics at the time is presented. The Storegga tsunami was caused by alarge (~3200 km3) submarine slide that generated waves of up to 40m on the Norwegian coast, 20m in theShetlands, before reducing to several meters along the UK coastline. It left behind a number of deposits aswidespread as Greenland and Denmark. The wave is recreated using up-to-date palaeobathymetricreconstructions and the tsunami event is simulated in conjunction with tidal forcing. The slide is initiated at severalpoints in the tidal cycle to assess the effect it has on timing and wave run-up at key deposit sites along the UKcoast, as well as the Faroes and Norway. There are non-linear effects that act between the tsunami wave and thetidal wave that mean the effects of tides cannot be simply added on afterwards. The work shows the need for arange of disciplines to work together to fully understand past tsunami events, which in turn are crucial tounderstanding future risk, even in regions that experience only infrequent events.