Roger, J.H.M.; Gusman, A.R.; Burbidge, D.R.; Davison, A.; Fensom, J. 2024 A catalogue of tsunami synthetic waveforms at DART locations. GNS Science report 2024/14. 25 p.; doi: 10.21420/N0SX-J095
Abstract
Aotearoa New Zealand is exposed to tsunami hazard from local, regional and far-field sources. In order to quickly assess whether a tsunami has been triggered by an earthquake or non-earthquake source, a network of 12 deepwater pressure gauges, also known as Deep Ocean Assessment and Report of Tsunamis (DART) stations, was designed, purchased and then fully installed by 2021. However, the sea-level records communicated in near-real-time by the DART stations to the National Geohazards Monitoring Centre (NGMC) can sometimes be difficult to interpret. To help assess the threat to Aotearoa New Zealand from these records, we have used the scenarios from a pre-existing database of tsunami threat maps to produce a set of synthetic tsunami waveforms at the locations of the DART stations for each of the scenarios in the database. The threat-map database is currently used to generate tsunami threat maps by the NGMC once an accurate earthquake magnitude and location is determined. This study provides some additional information for each of these threat maps, namely, the tsunami waveforms at the DART locations for the scenario underpinning the map. We use these synthetic waveforms to produce a new set of maps, one for each scenario in the database. The maps show original tsunami threat maps plus the synthetic tsunami waveforms at each of the 12 DART locations for that scenario and its tsunami travel time to each coastal zone offshore Aotearoa New Zealand. The resulting maps can then be used by the Tsunami Expert Panel and others to assess how well the actual tsunami fits the synthetic waveforms at the DART stations during an actual response and thus whether the threat levels need to be revised. These can also be used to estimate the tsunami arrival times (first arrival and first time it crosses the marine threat threshold) in Aotearoa New Zealand for that source. The new maps will also be useful for training and exercise purposes. This report summarises the overall objectives of this part of the DART project, describes how the new maps were generated and then explains the details and format of the new maps. It also provides application examples with two past events, i.e. the 2021 Matthew Island (south Vanuatu) and 2021 Raoul Island (Kermadec) tsunami. (auths)
