Human responses to catastrophic natural events form an important research theme in archaeology. Using excavation and radiocarbon data, this article investigates the socio-cultural impact of the mid-first-millennium AD Tierra Blanca Joven eruption at San Andrés, El Salvador. The data, along with an architectural energetic analysis of the Campana structure at San Andrés, indicate that survivors and/or re-settlers made considerable efforts to construct monumental public buildings immediately following the eruption, using large quantities of volcanic tephra as construction material. Such re-building played important religious, social and political roles in human responses to the eruption. The study contributes to discussions about human creativity, adaptation and resilience in the face of abrupt environmental change.