Long Wave Models Underpinning New Zealand’s Tsunami Hazard Assessment and Mitigation Planning
Presentation
Authors: Wang X., W. Power, A. Gusman, J. Mountjoy, C. Holden, J. Roger, and B. Burbidge
Event: Fluids in New Zealand
Summary: This invited oral presentation covered recent model developments supported by BTW, e.g. tsunami generated by mass failure and air pressure waves from volcanic explosion applied in the HTHH volcanic tsunami study.
https://sms.wgtn.ac.nz/foswiki/pub/Events/FiNZ2023/Programme/FiNZProgrammeFinal.pdf(external link)
New Zealand faces tsunami threat from a range of tsunamigenic sources, including crustal and subduction zone earthquakes, subaerial and submarine landslides, and offshore volcanic activities. Recent research reveals that over the past 7000 years 10 possible subduction earthquakes occurred along the Hikurangi margin which poses the biggest tsunami threat to New Zealand.
Tsunami simulation models have been playing crucial roles in evaluating tsunami hazard potentials of these tsunamigenic sources, calculating tsunami hazard parameters for early warning and forecast, and providing quantitative inputs to tsunami hazard mitigation planning and decision-making. Most of widely used tsunami simulation models, such as MOST, TUNAMIN1/N2, and COMCOT, solve governing equations based on long-wave assumptions together with specially designed numerical schemes to achieve a balance between modelling accuracy and computational efficiency for tsunami simulations.
This presentation provides an overview of tsunami models, modelling techniques, and model advances to meet increasing challenges in tsunami hazard research and hazard mitigation applications, with a particular focus on COMCOT model for tsunami modelling applications. COMCOT (Cornell Multi-Grid Coupled Tsunami) model has been widely used by researchers to study various aspects of tsunami, including source mechanisms, transoceanic behaviours, coastal impacts, as well as effects of rivers, tides and sea level rises on tsunami hazard risk assessments. It simulates a wide range of tsunami processes, including its generation, propagation, run-up, and coastal inundation.
Initially born at Cornell University, USA, this modelling tool has been under development at GNS Science, New Zealand since 2009 to underpin its tsunami research and modelling studies. Multiple source mechanisms, such as earthquakes, landslides, ground-motions, inflow conditions, and air-pressure anomalies, have been developed and dynamically coupled with tsunami simulations. We will introduce some major features and functionalities of this model and present its recent applications in tsunami modelling and research studies in New Zealand, including tsunami hazard assessment for Scott Base redevelopment in Antarctica, tsunami evacuation zone developments in Canterbury, landslide tsunami and ground-motion induced seiching in Lake Tekapo, and tsunami waves excited by air pressure waves from the 2022 Hunga Tonga Hunga Ha’apai volcano eruption.
