Warning systems represent a critical element of the communication landscape and are aimed at providing information so people can take protective responses to various perils. While many warning systems tend to focus on the technical capabilities of providing warning information, warning systems in fact comprise a number of elements, all of which are needed for effective responses to occur. Kelman and Glantz (2014) summarize these aspects as risk knowledge, monitoring and warning, dissemination and communication and response capability. Basher (2006) and Harrison et al. (2020) argue that given effective responses are a key outcome of a warning system, a people-centered approach should be taken to warnings. This is reflected in the United Nations Office for Disaster Risk Reduction (UNDRR)1 definition of an early warning system which states it is: “The set of capacities needed to generate and disseminate timely and meaningful warning information to enable individuals, communities and organizations threatened by a hazard to prepare and to act appropriately and in sufficient time to reduce the possibility of harm or loss” (United Nations International Strategy for Disaster Risk Reduction (UNDRR), 2009, p. 12). Consequently, in developing an effective warning system it is important to understand the environmental, social and experiential context in which humans are located, to be able to identify how they might best receive, interpret, and respond to warnings, and then utilize that in warning system development (McBride et al., 2022).
Warnings can be disseminated and received for a wide range of perils, including natural hazards such as severe weather, flooding, volcanoes, tsunami and landslides. With the progression of science and technology, earthquake early warnings (EEW) are now also delivered to citizens in a number of countries including Japan, Taiwan, Mexico, South Korea, the West Coast of the United States of America (USA), Sichuan China and Peru (Allen and Melgar, 2019; Fallou et al., 2022; McBride et al., 2022), among others. An EEW comprises advanced notification of earthquake shaking, delivered by a device such as a mobile phone or stand-alone alerting device, or via channels such as the media. The ability to send such a notification is dependent upon detecting an earthquake that has already occurred (e.g., by detecting the earthquake with sensors at its source or via P-waves) and sending out a warning in advance of the arrival of shaking from S-waves (Given et al., 2018).
Most warnings are usually only issued for locations anticipated to receive strong shaking, as this is where damage, injury, and potentially death may occur (Allen et al., 2018; Allen and Melgar, 2019; Allen and Stogaitis, 2022). Notification may be received anywhere from a few seconds to minutes before shaking ensues; however, most warnings will be in the range of seconds to tens of seconds, rather than minutes (Minson et al., 2018). In some instances, if a person is located very close to the epicenter of an earthquake, there may not be time for a warning and the notification might arrive after shaking has started. In addition, delays to delivery of alerts including technological latencies in alerting channels, like cell broadcast or similar systems, will further delay when an alert can be delivered (Prasanna et al., 2022).
Upon receipt of a warning notification, citizens have the opportunity to take action to protect themselves from the incoming shaking. The actions that people might take vary from country to country. In the United States of America, for example, people are usually advised to protect themselves by performing Drop, Cover and Hold On (DCHO) when shaking occurs (Jones and Benthien, 2011; McBride et al., 2022), with additional advice provided on other protective actions for specific circumstances such as when driving (Washington State Emergency Management Division, 2017). Similar advice is promoted in places like Japan and Aotearoa New Zealand, where the message has been simplified to Drop, Cover, Hold (DCH) (McBride et al., 2019; Vinnell et al., 2020). This advice is relevant because most buildings in such countries are expected to perform adequately in an earthquake. However, in other countries where construction is not as sound (e.g., Mexico) advice focusses on evacuating buildings on receipt of an EEW (Santos-Reyes, 2020; McBride et al., 2022). Japan, which has had an official EEW system operating since 2007 (Fujinawa and Noda, 2013), also provides advice on a variety of other safety actions to take on receipt of a warning (e.g., stopping elevators and getting off at the nearest floor; Japan Meteorological Agency, 2019).
Influences on People's Ability to Respond to EEWs
People's ability to respond to EEWs may be confounded by a range of factors. In the first instance, timing can be an issue. Where the time between a warning and the commencement of shaking is very short (i.e., a few seconds) citizens might only be able to stop and stay still or DCH (Nakayachi et al., 2019; Becker et al., 2020a). As warning timeframes increase, the opportunity for taking further safety actions or evacuating a building is possible. However, this opportunity also creates the added possibility of injuries if people are still moving as shaking commences (Shoaf et al., 1998; Johnston et al., 2014; Horspool et al., 2020). Given EEW timeframes are often so short (e.g., see Becker et al., 2020b for Aotearoa New Zealand modeling), consideration about what actions to take needs to occur well in advance of an earthquake, and is best achieved through education programmes and practice of drills (Vinnell et al., 2020). Arguably, EEW struggles to meet the definition from the United Nations International Strategy for Disaster Risk Reduction (UNDRR) (2009), with “sufficient time to reduce the possibility of harm or loss” being at issue here, as EEW may not provide this given its technological and physical limitations. Even with faster alerting channels and improved technology, there may always be some physical limitations to the system, such as a late alert zone, where the earthquake's epicenter is too close to an area for it to be categorized and calculated by algorithms, let alone sent out via various alerting channels before shaking arrives (Minson et al., 2019; McBride et al., 2020).
Second, citizens' desire and ability to act upon an EEW is influenced by a range of cognitive, social, and affective factors. Some of these aspects can directly influence people's responses to warnings, while others have a more indirect influence on the process. People's previous experiences of earthquakes are a part of this mix. Experience can be described in many different ways, an issue that has been highlighted and which makes it difficult to draw comparisons between studies (Becker et al., 2017). For this paper, we use the terms direct, indirect, vicarious, and life experience as defined by Becker et al. (2017). In terms of earthquakes, direct experience includes physically feeling strong shaking, or being impacted through injury or loss. Even direct earthquake experiences are highly variable, by frequency, intensity and context. Indirect experience includes being exposed indirectly to an event (e.g., having travel or employment disrupted) or observing a local event. Vicarious experience includes occasions where one might interact with friends and family with regard to a disaster, or observe a disaster in the media, rather than a disaster having a direct or indirect impact upon themselves. Vicarious experience can also extend to educational efforts including drills and exercises, which develop procedural knowledge as to what protective actions to take (Johnson et al., 2014; McBride et al., 2019), or when people are exposed to disaster scenarios but do not live through those disasters directly. Life experience is a fourth type of relevant experience where people might refer back to other adverse events or situations in their lives (e.g., experiencing a health issue, a car or work accident, power outages, crime, war) in understanding how they might respond to an earthquake (Norris, 1997; Paton et al., 2000; Becker et al., 2017).
The Influence of Previous Experience on Responses to Earthquake Threats
Previous research highlights the diverse ways in which experience can affect people's responses to earthquakes. Given the relatively recent emergence of technology that has made EEW more accessible for use, most research has been completed in an earthquake preparedness context, as opposed to a warnings context. Some researchers have found that earthquake experience can be a driver of preparedness activity (e.g., Kiecolt and Nigg, 1982; Lehman and Taylor, 1987; Mileti and Fitzpatrick, 1992; Mileti and Darlington, 1997; Lindell and Perry, 2000; Tanaka, 2005; Dunn et al., 2016; Becker et al., 2017; Vinnell et al., 2017; Doyle et al., 2018), while others have found the opposite (e.g., Mulilis et al., 1990; Farley, 1998; Lindell and Prater, 2002; Basolo et al., 2009; Bourque et al., 2012; Lindell, 2013; Shapira et al., 2018).
The nature of people's experience appears to be key to whether previous experience will enhance preparedness or not. Experiences such as being directly impacted by an earthquake (e.g., experiencing damage, loss or injury; Jackson, 1981; Turner et al., 1986; Blanchard-Boehm, 1998; Lindell and Prater, 2000; Nguyen et al., 2006); being indirectly impacted (e.g., evacuating following an earthquake, participating in rescues; Becker et al., 2017; Doyle et al., 2018), or being vicariously affected in a more personal way (e.g., experience of loss by a family member; Turner et al., 1986) have been identified as influential in motivating people to prepare for future earthquakes. However, as Lindell (2013) highlights, even these types of experiences have their own unique nuances which influence decisions about whether to prepare or not, and how to prepare.
Additionally, researchers have found various mediating factors that influence the experience-preparedness process. These include such aspects as risk perception (Solberg et al., 2010; Bourque et al., 2012; Bourque, 2013; McClure et al., 2015; Dunn et al., 2016), biases stemming from certain perceptions such as optimism and normalization biases (Weinstein, 1989a; Mileti and O'Brien, 1992; Helweg-Larsen, 1999; Spittal et al., 2005; Shapira et al., 2018), levels of concern, fear or anxiety (Dooley et al., 1992; Rüstemli and Karanci, 1999; Karanci and Aksit, 2000; Siegel et al., 2003; Heller et al., 2005; Dunn et al., 2016; Paton and Buergelt, 2019) and people's ability for personal control (Rüstemli and Karanci, 1999). Research in Aotearoa New Zealand particularly has shown that potential barriers to preparation behavior such as cost or logistics are less influential than cognitive barriers (McClure et al., 2015; Vinnell et al., 2021).
Many of the factors and biases outlined above are evolved protective mechanisms to help individuals cope in response to an overwhelming number of risks that we encounter in our daily lives. Such risks can range from the lower likelihood high impact events such as an earthquake through to higher likelihood less widely impacting events such as car accidents. Biases work to reduce feelings of fear about risks; for example, optimism biases involve an individual believing they are less likely to suffer negative consequences than other people like them (Weinstein, 1989b), despite this being probabilistically flawed. Normalization bias involves the individual believing that all future events (e.g., earthquakes) will be similar to all past events that they have experienced (Mileti and O'Brien, 1992; Mileti and DeRouen Darlington, 1995; Johnston et al., 1999). Therefore, if a person feels a previous earthquake was not bad in terms of shaking or impacts, they might consider future earthquake risk to be low and optimistically not bother preparing, or not intend responding to an EEW. These psychological mechanisms are useful as they allow individuals to function in the face of a multitude of risks but pose a challenge which must be overcome when trying to motivate preparedness. Our understanding of how these factors operate is therefore important to unpacking how experience might influence preparedness, and potentially future responses to EEW.
Several theories have been developed to explain and predict people's behavior in hazard contexts, including in response to warnings, including the Protective Action Decision Model (PADM) (Lindell and Perry, 2012); Protection Motivation Theory (PMT) (Tanner et al., 1989), and Community Engagement Theory (CET) (Paton, 2013). Theories from other areas of behavioral sciences have also been applied in the hazard context, including Emergent Norm Theory (ENT) (Wood et al., 2017) and the Theory of Planned Behavior (TPB) (Vinnell et al., 2021). These models propose a large number of factors which can influence both people's preparation behavior and response behavior, including environmental and social cues; information about the peril/warning itself; exposure to that information; perceptions about the threat, actions, and what others think; and factors related to the current situation. Such inputs will determine an eventual response such as undertaking protective action, conducting an information search, or an emotional response. Sometimes people will also reach a conclusion that they will do nothing.
While much research has focussed on warnings in the context of other perils (e.g., tornadoes, hurricanes, volcanoes), there has been very limited work on responses to earthquake early warning, likely due to the relatively recent nature of emerging technologies to support widespread warning responses across different countries. Studies that have been conducted have focussed on perceptions of EEW and either intended or actual responses to earthquake warnings. The following outlines these studies.
Prior Studies on EEW Perceptions, Experiences and Responses
First, it has been important to understand how useful people perceive EEWs to be. We know from the PADM model and from other studies, that perceptions about preparedness (in this case a warning system) and protective actions are influential in people's decision-making about whether to undertake actions or not (Lindell and Perry, 2012; Johnston et al., 2013; Becker et al., 2015; Vinnell et al., 2017). If an EEW system is perceived as useful, and the warnings actionable, then citizens may be more likely to use it. Results from research on the perceptions of EEW usefulness have been mixed, however, depending on the context. For hypothetical EEW scenarios, citizens have expressed strong support for EEW utility (Dunn et al., 2016; Becker et al., 2020a,b). In real warning situations, some researchers have found that people do consider warnings useful, even when issues arise with warning systems, such as receiving false alerts or late alerts after shaking has occurred (Nakayachi et al., 2019; Fallou et al., 2022). However, other research by Santos-Reyes (2020) has found that perceptions of warning systems' usefulness can fall following a devastating earthquake (i.e., a Magnitude 7.1 earthquake in Mexico on 10 Sept 2017 when warnings were not provided in enough time before shaking for people to act). Given the 2017 earthquake in Mexico caused damage, injury and deaths, it was perhaps the severe impacts from this experience that influenced people's subsequent perceptions about EEW's utility, and possibly also recalibrated people's understanding of its true effectiveness.
Second, research on citizens' actual and intended responses to alerts have also had mixed conclusions. Studies from Japan suggest citizens are more likely to mentally prepare and stop and stay still on receipt of a warning, rather than take a specific protective action (Nakayachi et al., 2019). Reasons for the Japanese population not taking specific protective actions on receipt of an alert appear to relate to previous experience, where prior warnings have not resulted in strong shaking, leading to lower risk perception and optimism that strong shaking will not follow warnings in future. Data from a Peru survey highlight a similar lack of protective action, whereby participants reported that on receipt of an alert, they more often warned people nearby or waited for shaking to begin (Fallou et al., 2022). These studies show that having previous experience of EEWs does not necessarily translate into people taking protective action for alerts, for various reasons. However, when surveying intended responses of citizens from other countries without operational EEW systems (e.g., United States of America prior to EEW roll-out on the West Coast, and Aotearoa New Zealand), people were more likely to intend to take protective actions such as DCH (Dunn et al., 2016; Becker et al., 2020a), in comparison with Japan and Peru. Whether these intentions are accurate or not is questionable (Becker et al., 2020a). As an example, Dunn et al. (2016) found in their survey that 53% suggested they would DCHO, while only 20% had actually done so for an earthquake. Only future research will help us understand whether intentions predict actions in an EEW context.
Additionally, from an experience perspective, Dunn et al. (2016) looked at citizens' prior experiences of earthquakes and perceptions of EEW in a “willingness to pay” for warnings context (i.e., willingness to pay for an earthquake early alert app.). In their survey, respondents with previous earthquake experience had a higher familiarity with the concept of EEW, and were slightly more likely to consider EEW effective, in that they believed they could better protect themselves from earthquake risks. However, respondents with experience of an actual earthquake also had less willingness to pay for an EEW app., possibly due to the fact that most of their previous experiences only related to moderate shaking levels which were of limited concern. People who had vicarious experience of watching the “San Andreas” movie expressed more willingness to pay. The Dunn et al. (2016) survey highlighted some of the influences of previous earthquake experience on EEW, namely people's perception that EEW could provide them with a better outcome (i.e., positive outcome expectancy), and that different types of experience can be influential on the process (i.e., in this case, direct vs. vicarious experience), but in different ways.
The influence of previous experience is difficult to understand in the context of earthquake preparedness, let alone in a warning context. Given limited behavioral research on EEW, the effects of experience on earthquake warning response behavior is untested. Therefore, we undertook research to attempt to advance our understanding on this topic. Particularly, we were interested in understanding whether previous earthquake experience might influence both people's perceptions of EEW and their responses upon receiving an alert.
To do this we undertook a survey in 2019 in Aotearoa New Zealand. Given Aotearoa New Zealand had no comprehensive EEW system in 2019 (Prasanna et al., 2022), the survey focussed on a hypothetical EEW context. Within the survey, we asked a range of questions about preferred EEW system attributes and anticipated responses to EEW, of which the general findings are reported in Becker et al. (2020a). We also asked about people's experiences of previous earthquakes from a direct, indirect and vicarious experience perspective. We were interested in finding out what effect such experiences had on perceived usefulness of EEW and intended responses to warnings. This paper discusses key findings from the survey in relation to earthquake experience and EEW.