New Zealand Tsunami Exercise “Exercise Tangaroa”
By David Coetzee & Nora Gale
Exercise Tangaroa, held on Wednesday 20 October 2010, was a national, multi-agency exercise focusing on the national response to a distant source tsunami event. The exercise was led by the Ministry of Civil Defence & Emergency Management (MCDEM), with participation from the 16 CDEM Groups, central government departments, emergency services, lifeline utilities, and other agencies across the country. In all, over 100 agencies and companies took part, making it one of the largest civil defence emergency management exercises ever held in New Zealand.
The scenario for the exercise was based on a magnitude 9.1 earthquake off the coast ofCentral Peru in South America and focused on the lead-up to a tsunami arrival, stopping when the first waves reached the New Zealand coast.
The exercise was played in real time, with the first notification of the earthquake (and the start of the exercise) at 4:59 am. The exercise finished at 7.05pm the same day.
Information about a simulated destructive tsunami crossing the Pacific was communicated through simulated tsunami, earthquake and sea-level information bulletins issued (notionally) by the Pacific Tsunami Warning Centre (PTWC), the United States Geological Survey (USGS) and the Nation Oceanic and Atmospheric Administration’s National Data Buoy Centre (NOAA NDBC). These were sent to MCDEM as the national Tsunami Warning Focal Point (TWFP) and to other agencies that normally subscribe to PTWC bulletins.
Decision-making and notification down to the last stage before notifying the public withinNew Zealand was exercised. MCDEM analysed the simulated PTWC information with the support of the Tsunami Experts Panel, a science group coordinated by GeoNet, and subsequently issued national advisory and warning messages. The participating national and regional agencies responded to this information by considering appropriate warning and response at their levels. This resulted in local warnings, evacuations and welfare support within affected areas, most of them notional, but used as the basis for exercising response staff.
Expected maximum wave amplitudes (m) in deep water for the Exercise Tangaroa tsunami calculated using COMCOT tsunami propagation software.
Threat level estimates for 43 coastal zones along the New Zealand coastline were introduced during Exercise Tangaroa. These estimates were displayed on a map and are the result of significant modelling conducted by GNS Science (funded by MCDEM) over the last year. The maps were prepared by GeoNet and attached to MCDEM hourly updates. The threat level estimates are based on the expected maximum wave amplitude at shore at any point within each zone. This worked well as the first estimates could be distributed within the first two hours, allowing decision-makers at the regional and local level to assess the risk to their communities, and take appropriate steps. GeoNet applied further modelling to refine the estimates over the next hours and although they did not require significant adjustment, the maps were updated accordingly to provide the best possible indication of threat.
Overall, the exercise was a success. The national warning system messages were broadcast in a timely manner, local level Civil Defence responded quickly and appropriately, and a lot of useful information was gained. The evaluation process will continue until April next year, when the Exercise Report is expected to be completed.