Introduction

Natural disasters are considerable events that cause widespread destruction to the environment and loss of life. ¹ Disasters usually cause injuries and deaths, property losses, and infrastructure destruction, and can lead to short-term and long-term adverse effects on human health and well-being. ^{1–Reference Xu, Yong and Deng3} Existing literature indicated that disasters could result in post-disaster stress disorder, ^{Reference Galea, Nandi and Vlahov4,Reference Kiliç, Ozgüven and Sayil5} damage survivors’ quality of life, ^{Reference Calvo, Arcaya and Baum6,Reference Ardalan, Mazaheri and Vanrooyen7} and affect survivors’ health in the long run. ^{Reference Han, Wei and Zhao8} One of the most effective means to deal with threats caused by natural disasters is to improve household disaster preparedness capacity. ^{Reference Ma, Guo and Deng9} Being prepared for disasters can minimize damage to human health, lives, and property, significantly improving residents’ happiness, life satisfaction, and general health status. ^{Reference Qing, Deng and Xu10}

Disaster preparedness can be defined as the knowledge, capabilities, and actions “to effectively anticipate, respond to, and recover from, the impacts of likely, imminent or current hazard events or conditions”. ¹ Sufficient household preparedness for disaster reduction and prevention can effectively decrease the losses and harmful impacts of disasters, and shorten recovery time after disasters. ^{Reference Malmin11} Previous studies showed that disaster severity generally affected survivors’ disaster preparedness strategies when dealing with possible disasters in the future. Survivors who experienced financial or health damage during disasters tend to be well prepared to deal with disaster events. ^{Reference Osberghaus12} In the Great East Japan Earthquake, compared with others who did not suffer damage, survivors who experienced direct/indirect damage from the earthquake were relatively better prepared, mainly in basic preparedness, energy/heat preparedness, and evacuation preparedness. ^{Reference Onuma, Shin and Managi13} In the Typhoon Mangkhut, the severity of damage affected survivors’ willingness to prepare for future typhoons. ^{Reference Chan, Man and Lam14} In the Loma Prieta earthquake, survivors with little or no losses maintain lower risk awareness and may respond less to disaster warnings. ^{Reference Mileti and O’Brien15}

Also, previous studies examined the longstanding (several months or even years after the disaster) associations between disaster severity and disaster preparedness. ^{Reference Osberghaus12–Reference Chan, Man and Lam14,Reference Han and Nigg16–Reference Turner, Nigg and Paz18} However, only a few studies have discussed the long-term (5 y or more) effects of disaster severity on disaster preparedness, and the results were inconsistent. Eight years after the Wenchuan earthquake, survivors located in severely affected areas still have a strong tendency to purchase insurance to avoid disaster risk and tend to relocate their residences to prevent and avoid disaster events. The association of household risk perception with their aspiration to purchase insurance and relocation intention was significant and positive. ^{Reference Xu, Liu and Deng19} Eight years after the Loma Prieta earthquake, the effect of the severity of disaster damage on enterprises’ disaster preparedness actions and activities was still significantly positive-going. ^{Reference Han and Nigg16} However, a previous study in America assessed the relationship between disaster exposure as well as loss over the past 30 y and state-level preparedness. It was found that, at the state level, disaster preparedness was not associated with disaster deaths and injuries. ^{Reference Howe20}

Vulnerability, which can be considered the likelihood of an individual or household encountering certain risks, provides a wider perspective in disaster preparedness assessment studies. ²¹ Effects on disaster preparedness of disaster severity, may vary among survivors with different levels of household vulnerability. Household vulnerability is a set of conditions that negatively affects the ability of people to prepare for and withstand disaster. ^{Reference Alexander22,23} Household vulnerability may serve as a moderating variable, affecting the effect of disaster severity on disaster preparedness. Numerous studies measured household vulnerability using household economic situation and household members’ educational status. ^{Reference Zhang24–Reference Sun, Chen and Ren26} Research has shown that households with high levels of household vulnerability are more susceptible to disasters, experiencing property damage and even casualties. ^{Reference Sun, Chen and Ren26} Therefore, this study used household vulnerability to explore the moderating mechanisms underlying the association between disaster severity and disaster preparedness. Existing research has shown that higher household income was associated with better disaster preparedness. ^{Reference Yong, Lemyre and Pinsent27,Reference Wang, Han and Liu28} It is partly because, compared with low-income households, high-income households had a more robust economic capacity to undertake disaster preparedness activities and actions. Disaster survivors with sufficient resources may have greater self-efficacy or confidence to cope with threats from the disasters and be more likely to take aggressive defensive actions. ^{Reference Paek, Hilyard and Freimuth29,Reference Mulilis, Duval and Bovalino30} In addition, education may increase residents’ awareness about the seriousness of disaster damage and enhance the learning of preparedness knowledge and skills and the ability to obtain disaster information. ^{Reference Hoffmann and Muttarak31,Reference Muttarak and Pothisiri32} Disaster survivors with higher education levels showed better prevention, preparation, and action in response to natural disasters. ^{Reference Muttarak and Pothisiri32}

China has suffered severe losses from various natural disasters now and then. ^{Reference Zhou, Guo and Deng33,Reference Zeng, Guo and Deng34} The Wenchuan earthquake occurred in Sichuan Province on May 12, 2008. It is the most destructive earthquake with the broadest range, the heaviest disaster loss, and the most challenging disaster relief since the establishment of the People’s Republic of China. Existing literature indicated that disaster experiences have effects on disaster preparedness, whether in a short time or a long time (ie, from several months to 5 y). ^{Reference Malmin11,Reference Onuma, Shin and Managi13,Reference McCormick, Pevear and Rucks35,Reference Heller, Alexander and Gatz36} However, little is known about the long-term effects of disaster severity on disaster preparedness a decade after a disaster and the moderating effects of household vulnerability.

Exploring the long-term effects of disaster severity on disaster preparedness for disaster prevention, mitigation, and disaster management is highly essential and significant. Therefore, using data from survivors of the Wenchuan earthquake, we aimed to examine (1) whether the severity of the earthquake in 2008 had a long-term effect on survivors’ disaster preparedness in 2018 and (2) whether the long-term effect of disaster severity on disaster preparedness was affected by survivors’ household vulnerability in 2018.