This study examines the relationship between intermittent urban development and community memory through an ethnographic case study of Area A in Matsudo City, Chiba Prefecture, characterized by yatsu valley topography. Participatory mapping, historical document analysis, workshops, and ethnographic interviews were conducted to reveal how local residents’ memories and emotions are intertwined with physical environmental changes. The results show that the valley slopes and lowlands, once central to everyday life, have accumulated both positive memories of childhood experiences and negative memories associated with land development, environmental degradation, and institutional responses. These findings were interpreted within the framework of collective trauma, highlighting how the cumulative impact of successive development phases produced long-term distrust, loss, and anxiety among residents. The study demonstrates that community memory is not only an archive of local history but also a psychosocial foundation that influences responses to urban change. By clarifying these dynamics, the research contributes to theories of collective trauma in urban contexts and provides practical insights for external supporters and participatory approaches in sustainable community development.
Terada et al. (Thu,) studied this question.