Gusman AR, Burbidge DR, Power WL. 2020. An updated set of tsunami action maps for Kermadec earthquakes. Lower Hutt (NZ): GNS Science. 22 p. (GNS Science report; 2020/37). doi:10.21420/S9FW-AT75.
Abstract
In previous work Gusman et al. (2019) created a new tsunami scenario database containing Tsunami Threat Forecast maps of New Zealand for tsunamis caused by earthquakes around the Pacific Ocean, including the Kermadec subduction zone. The purpose of the database is to rapidly provide a Threat Forecast Map when an earthquake similar to one in the database occurs. The Threat Forecast Maps provide a threat estimate expected in each coastal region around New Zealand from the earthquake. However, an alternative approach would be to provide a ‘Tsunami Action Map’ instead of a ‘Threat Forecast Map’. Action Maps indicate the recommended immediate response needed for each coastal region rather than a specific threat level category. In New Zealand, Action Maps currently provide two levels of response, “Evacuate This Area Immediately” and “Area Under Assessment” for earthquakes in the central part of the Kermadec subduction zone above magnitude Mw7.9. Earthquakes in this area can reach New Zealand in 60-90 minutes, so a rapid response is needed before a well constrained location and moment magnitude for the earthquake can be obtained to make a Threat Forecast Map. In this report, we propose some updated Tsunami Action Maps for events in the Kermadec Source Area (177° E to 169° W and 25° S to 33° S) using the scenarios in the new database. We recommend eleven new Tsunami Action Maps for Kermadec earthquakes from Mw6.7 through to Mw8.7 and above. They are intended to be used whenever there is an earthquake with an epicentre within the Kermadec Source Area in the early part of a response. We also propose a new category in the Action Maps when no immediate response is likely to be required based on the given magnitude and epicentre. (auth)
