Tsunami risk in Australia: Facilitating community understanding
According to the Australian Bureau of Meteorology, the Australian coastline faces some 8,000km of tectonic plate boundary capable of generating tsunamis that could impact Australia. While commonly regarded as an irrelevant hazard in Australia, this assumption is unfounded. During the period since European settlement, Australia has experienced some fifty tsunamis. So, while an infrequent hazard, it does pose a risk, and one that could affect many people quickly.
For example, some 330,000 New South Wales residents live within a height of 10 metres above sea-level and within 1km of the coast or a coastal river. A large tsunami event could affect them within hours. For instance, the closest sources of tsunami risk for Australia’s eastern seaboard, the Puysegur Trench (south of New Zealand) could trigger a tsunami that could reach Australian shores in 2 hours. Allowing time to detect a tsunamigenic event, warning times of 90 minutes could be expected. Australia’s tsunami risk is thus greater than many people think.
Recognition of this risk prompted development of the Australian Tsunami Warning System (ATWS). However, a gap between the development of warning technologies and coastal residents’ ability to respond to a warning has been identified. If the ATWS is to realize its potential, people must know how the ATWS functions and be able to respond promptly (e.g., know their evacuation route, what to take with them etc.) should a warning be issued. To fill this gap, a team of Bushfire and Natural Hazard CRC researchers together with representatives of the NSW SES and Surf Life Saving Australia interviewed members of coastal community groups in NSW, WA and Tasmania living in at-risk coastal areas (below the 10-metre contour) regarding their beliefs about tsunami risk, warnings and preparedness.
People’s Beliefs About Tsunami
Interviewees described tsunami as fast moving, substantial bodies of water whose devastating consequences would create considerable destruction and leave people unable to do anything to help themselves. Some interviewees discussed how, if a tsunami affected Australia, its impact would differ from place to place depending on its size and local conditions (e.g., elevation, coastal characteristics). These views influenced people’s understanding of tsunami risk.
Lack of knowledge of Australia’s tsunami history (fifty tsunamis since European settlement), no knowledge of sources of tsunami that could affect Australia, and the absence of government and media discussion of tsunami risk in Australia led people to believe that tsunami risk was very low or non-existent. Consequently, they saw no need to attend to tsunami warning issues. Given that the tsunami risk faced by Australian coastal communities exceeds current awareness of the potential threat, this project was instigated to identify a) how to increase people’s understanding and acceptance of tsunami risk, and b) their ability to respond to warning.
Understanding and Accepting Tsunami Risk
People must believe that tsunami could affect them before they will adopt DRR recommendations. Interviewees proposed that community-based discussion of tsunami characteristics is the key to positively influencing risk acceptance. They suggested that programs be delivered in each community/locality by agencies (e.g., State Emergency Services, Surf Life Saving Australia, Coast Care) they believe play key roles in warning and response management. Any program must, they argued, accommodate local circumstances.
Interviewees argued that generalised (i.e., region-wide) information would lack local specificity and hinder both its acceptance and the likelihood of it motivating action. They suggested that discussions should be tailored to each location and cover: the potential magnitude of local events, the source and dissemination of warnings, travel times, using and local maps to plot inundation zones and identify evacuation routes, local safe places and evacuation centres. Developing local plans and actions would be vital to the success of any DRR program. Information on the roles of key agencies and sources available to develop their knowledge and planning (e.g., Tsunami: The ultimate guide) should be provided.
It would be costly for agencies to develop local information for all at-risk coastal communities. A more cost-effective approach involves encouraging each community to liaise with agencies while community members develop their local knowledge, plans and activities. Work in Tasmania (the Bushfire Ready Neighbourhood evaluation) illustrates the benefits that accrue from engaging community members in local DRR initiatives. The cost-effectiveness of this approach could be enhanced by agencies (e.g., SES, Surf Life Saving Australia, Red Cross) drawing on their local volunteer resources to facilitate this developmental process. Such an approach was endorsed by interviewees. Having identified how to increase acceptance of a potential tsunami threat, discussion turned people’s views about what could be done to enhance warning and response effectiveness.
Warnings and Warning Content
Most interviewees (90%) knew of the ATWS, but were unclear about who was responsible for getting warnings to them. Some believed it was the police, others the fire service, and some thought it was the Bureau of Meteorology. Regarding the dissemination of warnings, TV and radio (e.g., radio while travelling in the car to/from places, TV when at home in the evening) were the preferred media. Less certainty was expressed about text message warnings, particularly regarding differences in the trustworthiness of the sources. The use of sirens on beaches and town centres was discounted. It was believed that people ignore them, and doubts were expressed about their ability to direct people to evacuate the beach, head inland or vertically evacuate.
Next, attention turned to what people would do if they received a warning. An important issue here was finding that a warning may not act as a cue to action.
Most participants stated that, on receiving a warning, they would first seek verification from a trusted source (e.g., the ABC, BoM). After obtaining verification, they would contact family to check if they had received the warning. Only then would they evacuate themselves. No interviewee considered whether there would be time to do this (e.g., if a tsunami originated in New Zealand). If, however, local actionable information was included in warnings, they would be less likely to seek verification.
Views about including actionable information in warnings derived from people’s belief that preparing for tsunami was pointless, either because the threat was “non-existent” or, since people don’t prepare for common hazards (e.g., bushfires), they will not do so for “non-existent” events. The inclusion of actionable information in warnings was thus seen as a substitute for planning and preparedness.
Regarding actionable local information, suggestions included discussion about: areas affected; time until tsunami arrives; and where to evacuate to. At the very least, warnings should direct people to get to higher ground. People expected that a warning would advise what constituted a safe distance inland or vertically and the best evacuation action for them. Time limitations were not considered.
This approach is problematic. For example, warning times of 90 minutes would be insufficient for people to receive a warning, identify how to evacuate from their specific location when a warning is received and act. Factors such as the impact of stress on decision making and traffic congestion would slow people’s decisions and actions. Nor is it feasible to develop warning content and dissemination practices tailored to every coastal community. To be effective, residents must understand their local risk and plan accordingly, especially if a warning allows only ninety minutes to act.
A way forward suggested by some interviewees was to integrate tsunami preparedness into an “all hazards” process. This could involve discussing tsunami risk and preparedness in relation to more regularly occurring hazards such as storm surges and flash flooding.
The short warning times that could arise with tsunami mirror those associated with flash flooding (defined by the Bureau of Meteorology as occurring within 6 hours of storm rainfall, but often within less than 2 hours). Integrating discussion of response to tsunami warning with that on flash floods illustrates how adopting an all-hazards approach might work. An all-hazards approach could be complemented with community-based, local planning to accommodate the needs, goals, capabilities and expectations that exist across all stakeholder groups and areas. Strategies for doing so could capitalize on using volunteer resources to facilitate community engagement and thus people’s access to agency expertise and resources.
The authors thank the Bushfire and Natural Hazards Cooperative Research Centre for funding this project.
For more information, email Douglas.Paton@cdu.edu.au