Aftershocks: Home Loss and Long-Term Health after the 2011 Great East Japan Earthquake.

From hurricanes to earthquakes, natural disasters affect survivors in innumerable ways, including adverse effects on mental[1] and physical[2] health. Only a few studies have been able to assess a consistent set of health indicators both before and after a disaster due to the unpredictability of such events. However, in a study recently published in Environmental Health Perspectives,[3] a team of researchers was able to use preexisting data from the Japan Gerontological Evaluation Study to assess a wide array of health and well-being outcomes before and up to 9 years after the 2011 Great East Japan Earthquake.

The authors used data from a cohort of older individuals who came from the city of Iwanuma. The tsunami that followed the earthquake killed more than 180 people in Iwanuma, inundated nearly half the city, and destroyed 5,542 houses. Most of the 2,167 individuals in the current study sustained some degree of damage to their homes during the 2011 disaster; 4% suffered a complete home loss.

The Great East Japan Earthquake and related tsunami completely destroyed 122,000 dwellings in all and damaged another 1 million, according to estimates from 2021.[5] Image: © Gallo Images/Contributor via Getty Images.

The study examined the longitudinal associations between complete home loss specifically and 34 health indicators categorized as physical health, mental health (e.g., symptoms of depression or posttraumatic stress), health behaviors/sleep (e.g., dozing off during the day), social well-being (participation in society), cognitive social capital (perceptions about social relations in the community), subjective well-being (happiness and life satisfaction), and prosocial or altruistic behaviors (e.g., sharing). This “outcome-wide” framework—namely, assessing the relationship between a single exposure and multiple outcomes—is a relatively new approach.[4]

“Epidemiologic research on disaster survivors has focused on mental health problems as an outcome,” says lead author Koichiro Shiba, a postdoctoral research fellow at the Harvard T.H. Chan School of Public Health. “We know little about how a disaster influences key aspects of human well-being that cannot be captured by looking at mental health alone. This knowledge gap motivated us to employ the outcome-wide framework to examine the relationship between the disaster experience and well-being.”

After 9 years, complete home loss was associated with increased symptoms of posttraumatic stress, depression, and hopelessness. People who lost their homes were also more likely to experience daytime sleepiness along with lower levels of trust in the community, community attachment, perceptions of mutual help in the community, and prosociality. The researchers saw more modest associations between complete home loss and having more chronic conditions, higher body mass index, and decreased happiness. Home loss was not associated with the remaining indicators.

“The most surprising result to me was the strong association between home loss and decreased social capital; it is notable that the association persisted even nine years after the disaster,” Shiba says. “By that time, buildings in the flooded area had been rebuilt and people had already moved out of the temporary shelters and lived in permanent housing. It is difficult and takes time to reconstruct social capital once it is destroyed, highlighting the importance of efforts to preserve preexisting social capital.”

“This is an excellent piece of scholarship. The longevity of the disruptive effect is astonishing: 9 years post-event, participants are still experiencing distress related to the earthquake event,” says Katie E. Cherry, the Emogene Pliner Distinguished Professor of Aging Studies at Louisiana State University and author The Other Side of Suffering, which covers her research on survivor recovery after Hurricanes Katrina and Rita. “Most important from a methodological point of view is the authors’ use of a prospective design,” she says, explaining that the availability of pre-event data allowed for a cleaner assessment of earthquake exposure effects.

“It’s nice to see the authors’ inclusion of social capital and mental health consequences as outcome variables,” Cherry adds. Yet she found the notion of cognitive social capital to be conceptually ambiguous. The authors included in that term trust and mutual help in the community, as well as community attachment. “There is a large [body of] literature on social capital, which is a well-established social science construct,” Cherry says. “To my knowledge, there may be a dimension of social capital that is cognitive, but I am not aware of a ‘cognitive social capital.’”

“Although we intuitively understand that losing a home during a natural hazard or disaster is incredibly harmful, this study has used extensive quantitative data from more than 2,000 survivors over a decade to show how broadly damaging it can be,” says Daniel Aldrich, a professor of political science and public policy at Northeastern University. “It is not just the loss of one’s physical property that changes one’s life. It is also the forced relocation that follows which pulls people away from their pre-disaster family, neighbors, and friends. In short, they lose their social networks, and these networks are powerful determinants of social and mental health.”