Raising Seawalls in Japan

by Denis Byrne

Over the last few years on the islands of the Seto Inland Sea, in Japan, new reinforced-concrete seawalls approximately one metre high have been erected on the shoreline in front of old fishing villages and other settlements. Where existing concrete seawalls are in place, these have been heightened by laying a metre of new concrete on top of them. The walls form perfect horizontal lines, meaning they align with the surface of the Inland Sea (which connects to the Pacific via two major channels). In fact the line of the top of the wall is a projection of where the surface of the sea might be (or almost be) during a major storm surge, such as occurred several years ago when the sea spilled over the old seawalls and flooded some of the settlements.

A number of the islands of the Inland Sea are participate in the Setouchi Triennial, an art festival that mainly features outdoor sculpture and installations staged in abandoned houses and other old buildings in the ports and fishing villages which for decades now have been losing population to the cities. Stepping off the ferry on one of the islands, a Setouchi ticketholder might easily mistake one of the new seawalls for an art object. Indeed, in this respect, the concrete walls are similar to the exquisitely constructed stone breakwaters and retaining walls which foreign visitors to Japan sometimes have difficulty believing are ‘merely’ utilitarian [Fig. 1 Megijima stone walls].

fig-2-windwall-megijimaFig. 1 Wind wall Megijima

The new concrete seawall on Megijima Island runs along the seaward side of the narrow coastal road while on the other side of the road, running parallel, are the massive stone walls which residents have built to protect their houses from storm winds [Fig 2 Megijima wind walls]. Walking along this road in August 2016 I initially took the two kinds of wall to be completely different objects. But on reflection I appreciated their commonality: they each simply reassembled geological ‘resources’ in different ways. The granite for the stone ‘wind walls’ had been quarried and transported to the site, shaped into trapezoidal blocks and fitted together in patterns that reorder or mix up the relative position in which the stone occurred in its original geological context. In the case of the seawall, the immaculately ‘finished’ concrete may seem an entirely artificial product but it consists simply of stone broken down into a gradation of fractions: gravel-sized stone aggregate, grains of sand, particles of limestone and clay.

fig-3-seawall-miyanoura-portFig. 2 Seawall Miyanoura Port

The construction of both these walls has involved extracting stone from the geobody of the Earth as part of ‘furious destratification’ that Kathryn Yusoff (2016: 4) sees as characterising capitalism (though her focus is mostly on fossil fuel extraction). The stone and concrete walls on Megijima Island add their weight to the new strata, in the form of roads, cities, landfill sites and so on whose rapid expansion across the Earth’s surface gives meaning to the term Anthropocene.

The walls are examples of a very high standard of concrete formwork often seen in Japan. The surface of the concrete, when the forms are removed, is almost flawless. In the case of the seawalls, where new layers of concrete have been poured on top of existing walls or along old concrete quays, the new is perfectly sutured to the old [Fig 3. Stratified steps]. But whereas the old concrete is weathered

fig-1-seawall-megijimaFig. 3 Seawall Megijima

to a dark grey and is stained by mold, blobs of tar, spillages of oil, and rust from heavy mooring chains, the new concrete is pale grey and pristine. The old and the new concrete look like geological layers, or stratigraphic layers in an archaeological excavation. You could be forgiven for thinking they have been placed here as a lesson in stratigraphic sequencing.

The concrete seawalls on the islands of the Seto Inland Sea have not been built not on natural land surfaces but on reclamations, places where the ‘land’ has been extended out to form concrete quays for fishing boats and ferries. Concrete began to be used for port and seawall construction in Japan in 1875 (Kobayashi et al., 2011) but it was in the aftermath of the 1891 Nōbi earthquake that reinforced concrete became a major building material in the archipelago, ushering in a ‘vision of a concrete Japan’ (Clancy 2006: 213). This vision was realised especially in public works and industrial infrastructure along the coasts of Honshu and Kyushu, including in the construction of port facilities, oil refineries, oil storage tanks, shipbuilding yards, most of which were situated on reclaimed land. By the late twentieth century, Japan was the world’s biggest per-capita consumer of cement at a time when population growth rate was steadily falling. This was partly due to a massive post-1989 public works program designed to revive the economy. It never quite achieved that but it earned the country the moniker doken kokka, meaning ‘construction state’, a state which has become dependent on government-funded public works to keep the economy turning over. Nowhere are the results of this more apparent than along the more densely settled parts of Japan’s coast. Sixty percent of the coastline of the main island, Honshu, is today classified as ‘artificial’, which is to say that for the most part it is concrete.

One way of contemplating the concrete coastlines of Japan is travel along them, kilometre by kilometre, via Google Earth, zooming in to get a closer look at the ruins of an abandoned ship-building yard, zooming out to get an overview of the massive scale of the human intervention that has poured hectares of concrete where beaches and wetlands used to be. But we should be wary of being mesmerised by the human agency on display here. In her writing, Yusoff keeps drawing out attention back to the ‘geologic force’ that is at play in modern human life. In the case of Japan, it is not just that the burning of Carboniferous fossil fuel enabled the industrial economy that demanded the reclamation of the coast, it is that the patterns of human life down there on the ground (involving the consumption of sushi, the driving of cars and forklifts, the watching of TV) is energised by the burning of the fossilised vegetation of the Carboniferous. Also, when we look down on the concrete coast of Japan what we are seeing is not a strata of concrete/tarmac/landfill created in and of the Anthropocene but a strata that physically incorporates the stuff of earlier geological eras (e.g., the limestone and rock aggregate in the concrete, the petroleum in the asphalt).

Returning to the new concrete seawalls of the Seto Inland Sea, there is good reason to think the motivation for their construction was at least as much to do with bolstering the local construction industry, creating employment and winning votes as it was to do with protecting depopulated fishing villages from storm surges. These walls are a product, in other words, of the ‘construction state’. The spectre of imminent sea level rise, related to global warming, does not seem to have been a significant consideration in building them but there is an obvious circularity that links Japan’s addiction to concrete to anthropogenic sea level rise. The limestone and the other clay-like materials used in the Portland cement that is essential to modern concrete are ‘cooked’ at 14000 centigrade, leading to a situation in which the production of a tonne of cement generates roughly a tonne of CO2

(Rubenstein 2012). With global consumption of cement hitting 4.6 billion tonnes in 2014 and steadily rising, this is a figure that matters. On the islands of the Inland Sea, the new layers of concrete added to seawalls will protect against a sea that is rising partly in response to the manufacture of concrete.

In an anticipatory sense, it is as if the sea has already risen in the Inland Sea. In front of the old fishing village on Megijima a man lies resting on top of the new concrete wall and gazes out to sea. He is on a plane parallel to that of the sea and he is precisely one metre above the surface he may have rested on in 2012, before the wall was built [Figure 4 – man on seawall]. He rests on a surface which is as geological as it is architectural and like all of us his life is increasingly contingent on stratification.


Fig. 4 Man on Seawall


Clancey, Gregory. 2006. Earthquake Nation: The Cultural Politics of Japanese Seismicity 1868-1930, Berkeley: University of California Press.

Kobayashi, Ichiro, Sachiko Okada, Keiko Nagamura and Takafumi Yamanaka. 2011. Survey Report on the Port Construction Techniques for Masonry Quay, Graduate School of Science and Technology, Kumamtoto University, unpublished report.

Rubenstein, Madeleine. 2012. ‘Emissions from the cement industry’, New York: Columbia University Earth Institute http://blogs.ei.columbia.edu/2012/05/09/emissions-from-the-cement-industry/

Yusoff, Kathryn. 2016. ‘Anthropogenesis: origins and endings in the Anthropocene’, Theory, Culture and Society 33(2): 3-28.


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