The earthquake that had triggered the gargantuan waves on December 26, 2004, had been under the sea, just 255 kilometers southeast of Banda Aceh. The US Geological Survey estimated that the tsunami, which measured at least 9.0 in magnitude, released the energy of 23,000 atomic bombs. Nearly 228,000 people from more than a dozen countries were reported dead or missing, including 167,540 from Indonesia.

The disaster hit Aceh the hardest. The tsunami is the blight locals rarely speak about, but if one stays long enough, there is a chance it’ll make its way into conversations as dusk settles and people sit in their courtyards overlooking the ocean.

When the tsunami leveled the province, 463 local and international organizations and nonprofits scrambled to help with Aceh’s resurrection. They raised as much as US $7.7-billion, an unprecedented amount of aid money for a developing country.

Now, looking at Aceh nearly 15 years later, fissures in its recovery are still visible. The aid agencies had subscribed to the philosophy of “build back better,” intending to leave behind improved infrastructure and socioeconomic conditions, but foreign organizations parachuted in with little local knowledge and could not balance the communities’ needs with their own agendas. Agencies largely achieved the common goal of providing bigger and higher-quality houses, yet the expedited rehabilitation programs overlooked crucial long-term factors such as livelihood and disaster preparedness. Aceh would have been much worse off without the aid, but whether the goal of “better” was fully achieved is debatable.

Within the missteps are lessons that can be applied to future disaster responses, says Michael Boyland. He and his colleagues from SEI are in the process of evaluating how the build-back-better approach has played out in the coastal city of Tacloban in the Philippines, where recovery from 2013’s Typhoon Haiyan is ongoing. “Aceh served as a testing ground for what build back better is beyond principles, and almost a decade later, Tacloban’s recovery was likely better informed in terms of how to operationalize it and ensure more effective and holistic recovery interventions,” he explains.