The geological record of tsunamis in the anthropocene

44From the viewpoint of the material development of civilization, coasts-as the border between land and sea-have been an important environment and have provided a variety of services and wealth to humans. Ports and harbours have been developed and urban growth has occurred in coastal zones from ancient times with the aims of food production, river-marine traffic and military advantage (Kishida 2011). Although the area of coastal lowlands with elevations lower than 10 m occupies only 2 per cent of the earth’s land, almost 10 per cent of the world’s population is living in coastal lowlands (DESA 2011). Factories, repositories for resources such as oil and gas, and power plants have been constructed in coastal zones as a result of developments in commerce and industry. These facilities are absolutely imperative to maintain modern civilization and any failures to the facilities may cause fatal impacts to the sustainability of the daily life of modern people. Coastal environments have also played a crucial role in the cultural development of civilization. A variety of landscapes, such as sandy beaches and rocky shorelines, are formed in coastal zones reflecting local geology, climate, ecology and human activities. Coastal environments have not only been used for places of recreation, but have also been designated as natural parks and historical heritage that are preserved from further anthropogenic modification. In Japan, for example, a combination of white sandy beach and a thick forest of black pine trees is treated as a special cultural landscape and called hakusha seisho. This landscape has been a symbol of beautiful coasts and appeared in many paintings, photographs and literature. In 1987, one hundred places along Japan’s coasts were selected as hakusha seisho and are advertised as local tourism resources (Ministry of Forestry 2016). Miho no Matsubara on the western coast of Suruga Bay, Shizuoka (Figures 4.1 and4.2), has been registered as one component of the Mount Fuji World Heritage site because of the notable combination of the scenery of Mount Fuji and the hakusha seisho, a combination which has long offered much inspiration for artistic depictions (World Heritage Committee 2013). The preservation of coastal environments, including cultural landscapes, is important in terms of both commerce and culture. Even slight changes in the coastal landscape sometimes diminish the commercial and cultural value of the coast. People have applied unified measures to preserve coastal environments. In the case of Miho no Matsubara, the coastline is experiencing severe erosion due to massive extraction 45of sediments from the bed of the Abe River, up to 800×10⁶ m³ during the period of high economic growth in the 1960s. Later, the Abe River was identified as the main sediment source to maintain the sandy beach of Miho no Matsubara and sediment extraction has been prohibited since 1967. Littoral nourishment has been conducted to preserve the notable landscape (Shibayama and Kayane 2013).