- Title
- Preliminary modelling of a potentially tsunamigenic historic submarine landslide identified along the west coast of New Zealand’s north island
- Creator
- Mollison, Kendall C.; Bull, Suzanne; Arnot, Malcolm J.; Power, Hannah E.
- Relation
- Australasian Coasts and Ports 2021 Conference. Australasian Coasts and Ports 2021 Conference Proceedings (Te Pae, Christchurch 11-13 April, 2022) p. 692-698
- Relation
- https://www.coastsandports.org/2021-conference/
- Publisher
- Engineers Australia
- Resource Type
- conference paper
- Date
- 2022
- Description
- Submarine landslides are a mass movement of the seafloor that represent a potential tsunami source for adjacent coastlines. While the primary source of tsunami globally is co-seismic, approximately 7% of tsunami events are estimated to be submarine landslide induced. Submarine landslide-generated tsunami generally pose a more localised threat than co-seismic tsunami and have historically been associated with observations of large wave amplitudes and short arrival times at adjacent coastlines. This paper numerically models the failure of a historic submarine landslide that has been identified using shallow seismic reflection data from the northwest coast of New Zealand, offshore of Auckland. This historic submarine landslide is the largest identified offshore of New Zealand and is located along a margin which has experienced intense and repeated mass movement events. Preliminary numerical modelling was conducted for three different scenarios for the submarine landslide site identified. These scenarios were established based on the morphology of the submarine landslide site and include: (1) a smallest (best case) scenario, (2) a moderate scenario, and (3) a largest (worst case) scenario. The results of this preliminary modelling show that an extreme tsunami hazard would be posed by such an event if it were to occur in future, with maximum wave amplitudes at the coastline exceeding 70 m and water velocities exceeding 50 m/s. Arrival times for the west coast of New Zealand were shown to be as early as 18 mins but varied depending on distance from the tsunami source location, with several low-lying regions along the west coast of New Zealand shown to be particularly vulnerable. Additionally, the results presented here indicate that a submarine landslide event of this size would pose a tsunami threat to the east Australian coastline, with a 0.8 m amplitude wave arriving 1 km offshore of Sydney ~3 hr after submarine landslide failure and tsunami generation. While large tsunamigenic submarine landslides are a rare occurrence, initiated on relatively long geological timescales, the results presented here highlight a requirement for further high-resolution modelling and more extensive data coverage of the northwest New Zealand margin to assess how ubiquitous such submarine landslides events were in the past and the probability of such events in the future.
- Subject
- submarine landslide; mass movement; tsunami; coastal hazard
- Identifier
- http://hdl.handle.net/1959.13/1496602
- Identifier
- uon:54190
- Identifier
- ISBN:9780473647056
- Language
- eng
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