Evacuation time estimates for local source tsunami for Wellington suburbs

Abstract

The Wellington region is an active earthquake region. It sits above the Hikurangi subduction interface and is cut by a number of major local faults (e.g. the Wellington Fault, Wairarapa Fault and Wharekauhau Fault). Historical evidence exists for tsunami impacts on the Wellington coast from local source tsunami. Timely evacuation has proven to be the most effective means of reducing loss of life from tsunami, but a local source tsunami allows limited time for vacuation. Little time is available for official warnings and self-evacuation is recommended should a strongly felt or long-duration earthquake occur. Prompt evacuation together with a knowledge of evacuation routes and of the nearest safe zone minimises evacuation time and increases an evacuee’s chance of reaching the safe zone. To develop appropriate evacuation plans, two pieces of timing information are important: the predicted tsunami arrival time, and the time required to move to designated safe zones. This study provides an estimate of the time needed for people within coastal and other low-lying suburbs of the Wellington and Hutt Valley area to move to the designated safe zones. Combined with the tsunami arrival times available from previous work and with population information, it provides valuable information to inform risk-reduction and preparedness discussions and can be used to aid the development of evacuation plans. The modelling has identified a number of suburbs where immediate and efficient evacuation is necessary to avoid loss of life in local source tsunami. (auth)