How do people survive and move on from tragedies like last week’s terrorist attacks at home and abroad? When does a tragedy — whether human-made or natural disaster or a combination of the two — destroy a community, and when do they recover and thrive?

For me, it’s a question that’s both personal and professional. In 2005, my family’s home and possessions were destroyed by the floodwaters of Hurricane Katrina. Since then, I’ve researched why some communities rebound after crisis while others languish. The answer is in an often misunderstood concept called “resilience.”

Resilience is best understood as a characteristic of communities rather than individuals. Resilience isn’t personal grit; it’s the capacity of a neighborhood or community to respond, mitigate and adapt to crisis. People who face challenges reach out to their neighbors, friends, family and other networks to handle the issue emotionally, financially and logistically.

For instance, when my family and I learned our home was under floodwaters of Hurricane Katrina after we fled New Orleans, our recovery didn’t come from within. We had two young kids, no insurance on our destroyed property, and no idea what to do next. Communities of faith, family members, friends of friends, and the scholarly community helped us restart.

That’s where resilience comes from — from the other people with whom we are connected or, in modern parlance, our social network.

Consider the earthquake that struck Japan on March 11, 2011. My colleague and I gathered data on and analyzed more than 130 coastal cities struck by the 60-foot tsunami. We found that communities with stronger social ties and more trust before the disaster had a smaller percentage of their population killed than similar communities that were less connected. While many engineers believed that the seawalls constructed along Japan’s Tohoku coast would save lives, we showed that social infrastructure, not physical infrastructure, kept communities intact. Survivors we interviewed told us that they’d only made it through because a friend or neighbor had helped them from their vulnerable residences.

After Hurricane Katrina, communities with stronger internal cohesion and better connections to city officials fared best in rebuilding schools, stores and homes, which included, for instance, the Mary Queen of Viet Nam neighborhood in New Orleans. Communities that had strong internal cohesion but fewer connections to outside agencies and organizations – such as the Lower 9th Ward – did not display such resilience.

Japanese nuclear evacuees with more connections and friends had less anxiety and stress than those who were more isolated after that nation’s March 2011 disasters. The networks of people with whom we are connected – whether tenuously, such as a friend of a friend, or deeply, such as a family member – are critical resources during and after crisis.

Strangely enough, this is controversial. Since the attacks in Paris and San Bernardino, a number of pundits, psychologists and journalists have discussed the need for societal resilience in the face of terror and challenge. But one recent angry denunication of the call for resilience, in the New York Times, argued that it is “indistinguishable from classic American bootstrap logic when it is applied to individuals, placing all the burden of success and failure on a person’s character.” Jonathan Joseph and other scholars have argued that resilience lines up too well with neoliberal approaches that absolve governments of responsibility and allow them to do less.

That’s not so. A great deal of research has shown that communities themselves – not national governments — can deepen their reservoirs of social capital and improve their resilience to crises and disasters. Three kinds of community-based programs can connect local residents and build trust and reciprocity — the elements of true community resilience.

Community currency, or time banking

First, community currency, or time banking, encourages people to volunteer their time to help others, which builds a social network. In return for volunteering, residents receive “currency” or hours in a time bank that can be exchanged at local mom-and-pop stores, farmers markets or for bartered services — all of which also increase social connectedness. Community currency gives residents an incentive to leave their homes and get involved in projects ranging from trash pick-up to tutoring local school children, getting to know their neighbors. Studies have shown that time banking and community currency markedly increase trust and involvement and also local business-to-business interactions in a virtuous cycle.

Urban planning that creates public spaces in which to build community

Second, communities hoping to increase resilience must take urban planning and public space design seriously. Too few of our towns and cities have sufficient space for recreation, social interaction and leisure. Our social interactions are strongly determined by our surroundings, as architects have long known. For instance, the Tohoku, Japan-based program iBasho has created a free-for-use communal space where survivors of the 2011 disaster can come outside the drab, confined temporary housing units where some 50,000 people still live. The iBasho space includes a library for younger children, a cafe for adults and open use rooms for local NGOs. My colleagues and I have shown that the programs at iBasho – almost all of which are designed and managed by elderly residents — have strengthened local social networks and increased efficacy in their community. Broadly, societies need housing, streets and piazzas where residents can interact naturally, moving away from the isolation that can come with car-driven planning.

Building connections through social interaction

Third, a number of towns and cities, including Tokyo, San Francisco and Wellington, New Zealand, have set aside funds to encourage connections among neighbors. These include San Francisco’s NeighborFest program, where residents can receive thousands of dollars from the city to host a gathering to schmooze and listen to music; matsuri (festivals) sponsored by the local government where Tokyoites dance and enjoy snacks; and graffiti and school cleanup days in Wellington. Face-to-face interactions like these among community residents can build ties that will help them should challenges arise. Horizontal connections between residents are a critical part of resilience – as are vertical connections to decision-makers, civil society groups and government agencies.

Communities must be involved in knitting their own social ties 

Programs that build resilience are most successful when they are bottom up and community-driven. The Wellington Regional Emergency Management Office (WREMO) in New Zealand, for example, had a challenging time creating awareness of the serious tsunami threats that Wellington residents face from living in a coastal city with active seismic faults. After a number of unsuccessful programs involving posted signs and placards, organizers flipped their planning approach on its head, wondering whether the community itself could design a better program. Through series of meetings with local religious groups, immigrant support organizations and schools, they received a suggestion: Use blue paint to communally mark tsunami safe zones. Such an approach required no command of English and could be conveyed to children with ease. Wellington won one of the International Association of Emergency Managers Global Awards for Public Awareness for taking community input seriously.

All citizens certainly need government assistance and resources to deal with massive challenges like terrorism and natural disasters. But the ability to handle crises must be built locally, within each community. Strong connections help people in crises in three main ways: by offering mutual aid, enabling collective action, and enabling individuals to make better decisions about handling crisis.

A number of studies have illuminated how social ties enhance resilience. Emily Chamlee-Wright has shown how social capital and local narratives across New Orleans neighborhoods drove different expectations and therefore different recovery behaviors following Hurricane Katrina. The Australian Red Cross has published a manual for first responders training them to take social networks seriously, especially during fires. Rieko Kage has shown how better connected prefectures in post World War II Japan recovered more quickly from the devastation of that conflict. These scholars and NGOs can us understand the ways to make our communities and neighbors better able to manage challenge.

Daniel P. Aldrich is professor and co-director of the Security and Resilience Studies Program at Northeastern University, where he teaches in the School of Public Policy and Urban Affairs and the Department of Political Science. More about his research can be found here.