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We investigated responses to the 2013 Cook Strait earthquake sequence, New Zealand. This included two foreshocks (M5.7 and M5.8) and a mainshock doublet pair: M6.5 Cook Strait (CS) earthquake on 21st July and M6.6 Lake Grassmere (LG) earthquake on Friday 16th August. We examined relationships between preparedness, experience and beliefs during the earthquakes, as well as concern and subsequent preparedness actions. Results indicate that earthquake characteristics (e.g., time, location) influence the types of preparedness actions. While there was a reduction in new actions from the first mainshock doublet earthquake (CS) to the second (LG), there were a large number of participants who reviewed or revisited their prior actions, related to their beliefs about impacts, in a form of problem-focused targeted action. Females took more actions than did males, and had a higher rate of immediate aftershock concern. For all participants, concern was greater after the CS earthquake than after the full earthquake sequence, supporting the findings of McClure et al. (2016) that there is a limited window after an event to maximise the opportunity for effective preparedness initiatives. Findings additionally suggest that such post-earthquake preparedness initiatives should consider the impacts that elicited the highest rate of concern in an event, and should tailor messages towards them. While this earthquake sequence resulted in low levels of impact and damage, it presents interesting findings regarding how disruption (in lieu of major damage) influences earthquake preparedness actions, which is particularly important to understand in highly active regions often exposed to smaller impact events.

Although many countries have legislation requiring strengthening of earthquake prone buildings, there are significant obstacles to retrofitting these buildings to make them more resilient. This research examines actions in regard to earthquake prone commercial and public buildings in Wellington and checks on private homes following the 2010/2011 Canterbury earthquakes and the 2013 Seddon/Cook Strait earthquakes. The study obtained data on commercial and public buildings removed from the Wellington City Council Earthquake-prone Buildings List (EQPB List) from 2012 to 2016 due to various mitigation actions (e.g., demolition and strengthening). The study also obtained rates of self-initiated voluntary Quakecheck home assessments for the same period. Results indicate ongoing removal of significant numbers of buildings from the EQPB List in this period, with strengthening being the most frequent action. This finding suggests that despite real obstacles, various incentives including legislation are leading to consistent earthquake preparation over time, often before the legislative deadline. In contrast with the EQPB data, the Quakecheck data indicate a sharp but short-lived spike after the Seddon / Cook Strait earthquakes. As a marker of self-initiated mitigation action, this brief spike suggests that in the absence of relevant legislation or insurance incentives, citizens’ actions are only briefly influenced by the experience of an earthquake. These contrasting findings for EQPBs and Quakechecks suggest the value of legislation to drive mitigation actions for all buildings.

In July and August 2013, two moment magnitude 6.6 earthquakes occurred less than 80 km from the city of Wellington, New Zealand. The earthquakes were widely felt and injured over 100 people. Following the earthquakes, a survey was conducted in coastal suburbs of Wellington, one of which (Island Bay) had previously received sustained tsunami education and participated in community-based evacuation mapping. Both earthquakes were of insufficient strength and duration to meet the thresholds to prompt evacuation from coastal areas, as communicated in civil defence and emergency management messaging. As expected, the vast majority of residents did not evacuate, however, the surveys suggest that this was unrelated to the ground shaking intensity and duration, which were commonly over-estimated. Previous education is shown to have little influence on perception of potential tsunami impact, but responses showed accurate perception of safety in relation to the tsunami hazard zone. This study highlights the continuing need to actively engage with at-risk communities, both in terms of education and training around appropriate responses to natural or official tsunami warnings, and their active participation in the defining, designing and implementation of risk management practice at a community level.

Probabilistic statements can be a valuable tool for natural hazard risk communication, including forecasts. However, individuals often have a poor understanding of such probabilistic forecasts caused by them distorting their interpretations of event likelihoods towards the end of the time window and discounting the risk today. We investigated the use of an ‘anchoring’ time statement to mitigate this bias via an opportunistic survey run after the 2013 Cook Strait earthquakes, near Wellington, New Zealand. Participants rated their interpretations of likelihoods for an immediate aftershock forecast, and for an earthquake in the future. We explored the influence of aftershock and information concern, emotions and felt shaking, gender and education, as well as preparedness actions. The anchoring time window statement mitigated the skew in interpretations for the short (24 h to within 1 week) aftershock forecast statement. However, the skew still existed for the longer future earthquake forecast (7 days to within 1 year). We also found that heightened sensory experience (felt shaking) or emotional reactions (nervousness, fear, alertness) during the earthquakes was associated with an increase in the perceived likelihoods of future events. Gender was found to significantly influence results, with females rating higher levels of information concern and anxiety, and recording higher perceived likelihoods for the immediate aftershock forecast. Findings, including the importance of ‘anchoring’ time windows within a forecast to encourage immediate preparedness actions, support recommendations for effective crafting of these forecasts and warnings.

Research has shown that people often misinterpret probabilities reported by experts in the media. Previous research has found that people who are given a certain probability of a volcano eruption in a specific time window judge risk as higher in later time intervals within that window. The present study examines whether a similar pattern occurs with earthquakes and aftershocks. Participants in Wellington (N=102) and Christchurch (N=98) in New Zealand read expert forecasts of the risk of a Wellington earthquake and a large Christchurch aftershock within specified time windows, then estimated the risk in specific intervals across the time window. Participants judged the Wellington earthquake risk as higher toward the end of the 50 year time window whereas for a Christchurch aftershock, risk estimates initially increased then plateaued. Likelihood of preparing showed a different pattern to earthquake likelihood and was constant over the time windows. These findings suggest the influence of base rates and lay theories on interpretations of scientific forecasts.

Motivating household preparedness for earthquakes can be difficult, especially given the infrequent and varying nature of major events. Past research has shown that people's experiences contribute to their beliefs about whether, and how, they should prepare for earthquakes. Direct experience of a disaster can be a strong motivator of preparedness; however, most people will not directly experience a large damaging earthquake in their lifetimes. They instead need to rely on experience of small earthquakes, experience of different disasters, adverse life experiences (e.g. accidents), or vicarious experience. This paper explores the influence of such experiences on earthquake preparedness. The research found that experience has seven different influences on the preparedness process including: prompting thinking and talking; raising awareness and knowledge; helping individuals understand the consequences of a disaster; developing beliefs; developing preparedness; influencing emotions and feelings; and prompting community interaction on disaster issues.

The impact of uncertainty on Disaster Risk Reduction decision-making has become a pressing issue for debate over recent years. How do key officials interpret and accommodate uncertainty in science advice, forecasts and warnings into their decision making? Volcanic eruptions present a particularly uncertain hazard environment, and to accommodate this scientists utilize probabilistic techniques to inform decision-making. However, the interpretation of probabilities is influenced by their framing. We investigate how verbal or numerical probabilities affect decisions to evacuate a hypothetical town, and reasons given for that decision, based upon a volcanic eruption forecast. We find fewer evacuations for verbal terms than for equivalent numerical terms, and that the former is viewed as more ambiguous. This difference is greater for scientists, which we suggest is due to their greater familiarity with numerical probabilities and a belief that they are more certain. We also find that many participants have a poor understanding of the relationship between probability and time window stated, resulting in an incorrect assessment of overall likelihood and more evacuations for the lower likelihood version of two scenarios. Further, we find that career sector (scientist or non-scientist) influences evacuation decisions, with scientists tending to reduce the uncertainty by focusing on the quality and volume of information provided, while non-scientists tended to either acknowledge or suppress the uncertainty, focusing on actions to take. These findings demonstrate the importance of identifying communication strategies that mitigate different perceptions of forecasts, to both enhance end-user decision making and to prevent premature, delayed, or unnecessary actions.

Research has shown that experiencing a single disaster influences people's risk judgments about the hazard, but few studies have studied how multiple disasters in different locations affect risk judgments. Following two earthquake sequences in two different regions (Christchurch, Cook Strait), this study examined earthquake risk judgments, non-fatalism and preparation in two New Zealand cities that were near to one of those sequences (Christchurch in Canterbury, Wellington near Cook Strait) and in one city that was distant from both events (Palmerston North). Judgments of earthquake likelihood were higher after the Cook Strait earthquakes than before in Christchurch and the rest of New Zealand, but not in Wellington, where the baseline risk was high. However, participants in all cities saw the risk as more real, plausible, and important after these earthquakes, particularly in Wellington. Preparations following the earthquakes were also higher in Wellington and Christchurch (where non-fatalism was highest) than in Palmerston North. Causal attributions for (not) preparing differed across the three cities, as did non-fatalism. These findings suggest that the Christchurch and Cook Strait earthquakes had a combined effect on citizens' perception of the risk, particularly in Wellington. Such events create a valuable window of opportunity for agencies wishing to enhance preparedness.

Understanding how people interpret risks and choose actions based on their interpretations is vital to any strategy for disaster reduction. We review relevant literature with the aim of developing a conceptual framework to guide future research in this area. We stress that risks in the context of natural hazards always involve interactions between natural (physical) and human (behavioural) factors. Decision-making under conditions of uncertainty is inadequately described by traditional models of 'rational choice'. Instead, attention needs to be paid to how people's interpretations of risks are shaped by their own experience, personal feelings and values, cultural beliefs and interpersonal and societal dynamics. Furthermore, access to information and capacity for self-protection are typically distributed unevenly within populations. Hence trust is a critical moderator of the effectiveness of any policy for risk communication and public engagement.