When the shoreline disappears: seawalls, nagisa , and the perceptual conditions of coastal knowing in post-3.11 Japan

Following the 2011 Great East Japan Earthquake and tsunami, extensive coastal defences transformed not only the physical shoreline of northeast Japan but also the everyday conditions through which the sea can be perceived and encountered. This article examines these transformations at three sites within Kesennuma City, Miyagi Prefecture: Koizumi Beach, Kesennuma Inner Bay, and Ōshima’s Tanakahama Beach. Drawing on fieldwork conducted in 2023 and 2024, a photographic archive of approximately 450 images, and reconstruction planning documents, the analysis compares five dimensions of coastal infrastructure: horizon visibility, access permeability, vertical dominance, aesthetic texture, and information mediation. It develops nagisa (渚), understood as a rhythmic interface between land and sea, as a historically grounded diagnostic analytic for examining how coastal defence reorganises perceptual access. Koizumi’s high seawall largely removes the sea from inland view; Kesennuma’s negotiated waterfront defences preserve but unevenly mediate harbour visibility; and Tanakahama’s forested embankment softens defensive infrastructure while partially naturalising its boundary. These differences demonstrate that the perceptual availability of the coast is an outcome of design and negotiation rather than merely an aesthetic consequence of engineering. The article proposes epistemic resilience as a framework concerned with maintaining multiple, mutually correcting ways of knowing environmental risk. Rather than claiming to measure community knowledge or adaptive behaviour, it identifies the material conditions through which coastal infrastructure may support or constrain environmental attentiveness alongside engineered protection.