2.1. Overview of Nankai Trough Earthquake Countermeasures and Tsunami Risk in Nishiki

This section discusses the tsunami risk of a possible Nankai Trough earthquake in the Nishiki district of Taiki-cho from a seismological perspective. As a premise for this discussion, we first review national policy trends regarding Nankai Trough earthquake countermeasures. The 2011 Tohoku-Oki Earthquake (Great East Japan Earthquake) far exceeded expectations in terms of earthquake scale and tsunami damage. Considering this massive earthquake, the Central Disaster Prevention Council of the Cabinet Office compiled a scenario of “maximum class” earthquakes and tsunamis in 2012. However, the next Nankai Trough earthquake may not necessarily be the largest earthquake class. Based on scientific knowledge, the largest earthquake that could occur along the Nankai Trough in the future is called a “maximum-class earthquake,” and its frequency of occurrence is considered to be extremely low.

Nevertheless, the significance of considering the largest class of earthquakes and tsunamis is to eliminate unforeseen events and promote efficient disaster prevention and mitigation measures. Owing to the diversity of earthquake occurrence patterns in the Nankai Trough ¹⁹, predicting the exact type of earthquake that will occur based on current scientific knowledge is difficult. However, it would be inefficient for the government to establish multiple countermeasures against Nankai Trough earthquakes with various modes of occurrence, each of which would have a different magnitude. Therefore, disaster prevention and mitigation measures have been promoted based on the idea that although their frequency of occurrence is extremely low, the largest earthquakes and tsunamis that can cause extensive damage should be addressed if they do occur. Here, we focus particularly on the “Act on Development of Areas Resilient to Tsunami Disasters,” enacted in 2011.

Under the “Act on Development of Areas Resilient to Tsunami Disasters,” prefectural governors are required to set and announce the areas and depths of possible tsunami inundation (tsunami inundation assumptions) based on the “Basic Guidelines” formulated by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) in 2011, and notify the mayors of related cities, towns and villages. These basic guidelines state that a tsunami caused by a maximum-class earthquake should be assumed in the Nankai Trough area as well as in other areas.

Furthermore, municipalities are allowed to formulate a “plan for comprehensively promoting the creation of a tsunami disaster resilient community (promotion plan)” upon notification of the tsunami inundation assumption by prefectural governors. To facilitate creating this promotion plan, MLIT has developed the “Guidelines for Creating Tsunami Disaster Resilient Community Development Promotion Plans.” The guidelines emphasize the importance of not only DRR perspectives, such as the assumption of the largest class of tsunamis and multiple protections, but also community development and cooperation with residents and businesses.

Note: Areas marked in blue color are designated municipalities specifically to reinforce the evacuation plan against tsunami triggered by Nankai Trough Earthquake. Source: policy documents on “Measures Against a Nankai Trough Earthquake” of the Cabinet Office, Government of Japan (accessed August 20, 2025), and the Digital National Land Information of Japan.

Note: a: Nishiki Tower, b: 2nd Nishiki Tower, c: Former Nishiki Junior High School. Created by QGIS based on the MLIT’s “National Land Survey (tsunami inundation assumption data),” the Geospatial Information Authority of Japan’s “Designated Emergency Evacuation Site Data,” and the Oki-cho Nishiki District Tsunami Hazard Map. Tsunami inundation and washout areas during the 1944 Showa Tonankai Earthquake are from ²¹; inundation areas in 1854 (during the Ansei earthquake) are estimated from the hand-drawn map in ²⁰. The background is based on Geographical Survey Institute tiles (slope gradation map).

The Nishiki district of Taiki-cho, the focus of this study, has a population of approximately 1,500 people and 750 households (in 2020) and is located at the bottom of a small valley at the end of a bay on an intricate coastline facing the Pacific Ocean (Fig. 1).

Before World War II, Nishiki was an independent municipality; however, after municipal mergers in the Showa and Heisei eras, it became a district of Taiki-cho. However, even after the merger, Nishiki remains the only coastal area in the town, and the town’s Disaster Prevention and Safety Division is located at the Nishiki Branch Office of the Taiki-cho Town Hall.

Nishiki, located within the anticipated source area of the Nankai Trough earthquake, has been struck repeatedly by earthquakes and tsunamis. According to historical documents, the area between Tsukiji and Okuide, facing Nishiki Bay, suffered tsunami damage, such as loss of houses and flooding, even during the Ansei (1854) and Showa Tonankai (1944) earthquakes, which were much smaller than the maximum-class earthquake ^20,21 (Fig. 2).

During the Ansei Tsunami, the “Tsunami Brief Diary” records that “a tsunami was generated, rising over 6 meters above the shoreline,” and that “it was impossible to distinguish between the town and the sea” ²². In addition, the record at Nishiki Shrine describes that “80%–90% of the village was swept away by the tsunami” ²⁰. The Hoei Earthquake (1707), the largest Nankai Trough earthquake to date, is described in the “Ugura-son-shi” as ”the entire area from seashore of Nishiki to Omari was swept away without trace” ²³.

Although the “Tonankai Earthquake” of the Showa period was the smallest earthquake in the Nankai Trough known to date, Nishiki was hit by a tsunami approximately 6 m high, resulting in the death of 64 people and the destruction of 447 houses.

In the case of the maximum-class Nankai Trough earthquake, the coastal center of Nishiki is expected to be inundated to a maximum depth of 10 m ²⁴ (Fig. 2). Inundation depth is the water level measured from the ground at a location and is different from sea level or elevation; a 10-meter inundation depth is equivalent to the height at which the third floor of a building is submerged. In Nishiki, settlements have been formed in the inland areas of the northern part of the city. Although these villages appear to be safe from tsunamis because they are located on hillsides, they have a maximum inundation depth of approximately 5 m, which would submerge up to the eaves of the second floor. Therefore, in the event of a tsunami caused by a maximum-class Nankai Trough earthquake, the risk of residential houses being submerged in almost all areas of Nishiki district is considered high.

2.2. Tsunami Evacuation Scheme in Nishiki District

Based on the experience of repeated earthquakes and tsunami disasters, Taiki-cho developed its own tsunami evacuation scheme. In 1980, the Kisei-cho authorities designated December 7, the day the 1944 Tonankai Earthquake had occurred, as “Kisei-cho Disaster Prevention Day” to commemorate the occurrence of the earthquake. In 1989, the “45th Anniversary of the Tonankai Earthquake” was published by compiling the stories of disaster victims. From 1994 to 1995, the town authorities visited the areas affected by the 1993 Hokkaido Nansei Offshore Earthquake and the 1995 Great Hanshin-Awaji Earthquake and, as an administrative agency, launched a full-scale disaster prevention measure. The following three chief characteristics were identified ²⁵.

The first is to improve evacuation facilities. The basic literacy of tsunami DRR is to promptly evacuate vertically to higher ground. There are 30 designated emergency evacuation sites in Nishiki for tsunamis (Fig. 3). Twenty-seven of these sites are located on higher ground outside the expected tsunami inundation area in the event of a maximum-class Nankai Trough earthquake. The remaining three sites are the Nishiki Tower (Fig. 4), the second Nishiki Tower, and the former Nishiki Junior High School shelter, all of which are located within the expected 10-meter flood zone. The evacuation space in Nishiki Tower is located approximately 12 m above the ground, and the meeting room in the second Nishiki Tower is located approximately 15 m above the ground. Regarding the former Nishiki Junior High School, an evacuation space is provided on the roof of a three-story school building. Thus, all evacuation shelters in Nishiki district are located higher than the maximum tsunami inundation depth.

For emergency evacuation, considering not only the tsunami inundation depth, but also the arrival speed of the tsunami is essential. The maximum depth of tsunami inundation that would allow free evacuation is estimated to be 30 cm; however, in coastal communities in the central Nishiki district, the time from earthquake occurrence to 30 cm inundation is estimated to be at most 20 minutes ²⁴, which is generally insufficient to evacuate from a tsunami. However, because the 30 evacuation sites are located within a 5-minute walking distance for all residents in Nishiki (most of them on the slope immediately behind the housing), there is sufficient time to safely reach the evacuation sites, if evacuation activities are initiated as soon as the quake ceases.

The second measure is related to fostering a local disaster culture. Although old stone monuments related to the Tonankai and Ansei earthquakes have been handed down at the temple, town authorities have installed new monuments throughout the district, as well as signboards indicating the elevation of the location of these monuments. On December 7, “Disaster Prevention Day,” the town authorities, in cooperation with the fire brigade, hold a tsunami evacuation drill for residents. In addition, public lectures, workshops, observations, and excursions for residents have been conducted with the support of Mie Prefecture and the local university, and some results have been incorporated into the town’s disaster prevention plan. These are intended not only to visualize the collective memory of past experiences and pass them on to the next generation in the community, but also to localize the scientific knowledge of earthquakes and tsunamis.

Finally, and most uniquely, town authorities have worked independently of the central government and the Meteorological Agency to create their own local tsunami warning system. Under this system, even before the earthquake information and tsunami early warnings are issued by the Japan Meteorological Agency, when a town hall employee feels a strong 20-second horizontal tremor, he or she presses an alarm button located at the town branch office, and an evacuation instruction is issued through the outdoor warning device network. As it includes decisions based on lay knowledge ²⁶, it has limitations, such as not being able to respond to tsunami earthquakes or distant earthquakes; however, the town authorities have taken the stance of respecting such on-site decisions.

The tsunami evacuation scheme in the Nishiki district was proven to be effective after the 7.4-magnitude earthquake off the southeast coast of the Kii Peninsula that occurred late at night on September 5, 2004. Although 42 cities, towns, and villages in three prefectures were subject to tsunami warnings, only 12 cities, towns, and villages issued evacuation advisories, and the evacuation rate for residents averaged only 4.6% in the three prefectures. However, the Taiki-cho authorities issued an evacuation advisory before the tsunami warning by the Japan Meteorological Agency, and the evacuation rate of residents in Nishiki district reached 79%.

According to our survey on evacuation behavior during earthquakes ²⁷, approximately 72% of the respondents evacuated all or part of their families, and approximately 95% believed that a tsunami may follow the shaking. Nearly half of those who evacuated cited “self-determination” as the reason for their evacuation, and more than a quarter were prompted by warnings from the town. Although no major tsunami hit at that time, 93% of the respondents did not regret evacuation, and approximately 85% believed that it was inevitable to be slightly off mark for the safety of the residents and that this approach should be continued. Thus, many residents acquired the ability to evacuate based on their own judgment and formed a relationship of trust in the town authorities’ efforts. It can be said that the grassroots disaster preparedness of a small municipality in an earthquake-prone area was demonstrated.

2.3. Changes in Hazard Countermeasures After the Great East Japan Earthquake

Over the past two decades, particularly in the period following the 2011 Great East Japan Earthquake, the DRR in Nishiki has undergone significant changes. The focus of tsunami countermeasures in Nishiki has been on “evacuation” from tsunami, and emphasis has been placed on community-based disaster risk reduction mechanisms within a participatory framework. Thus, structural damage deterrence measures were secondary. At the time the tsunami evacuation scheme was devised, Nishiki district had only a 3.5-meter-high seawall, which was installed after Typhoon Vera in 1959. However, after the Great East Japan Earthquake, constructing a large seawall encircling Nishiki district was planned. The existing levee at the mouth of the bay was raised to 9.1 meters above sea level, a new 8-meter-high seawall was built behind the fishing port, and an estuary weir was planned to prepare for tsunami run-up to the river. In addition, the construction of an offshore seawall has begun to partition the waters behind the bay and is currently awaiting natural subsidence of the seafloor foundation.

Although these do not imply a shift away from the existing tsunami evacuation scheme, they suggest, at least in part, that town authorities have shifted the emphasis of their DRR measures to the physical expansion of disaster-mitigation facilities. The town’s disaster prevention and safety division explains that it is in response to the aging population and new central government guidelines for tsunami DRR, which were established after the Great East Japan Earthquake. However, undeniably, Taiki-cho as a remoter rural municipality struggling with financial difficulties used “disaster reduction” to attract subsidies from newly established projects such as the National Resilience Project.

However, there was a sense of crisis in the town authorities that the previous approach would not work. Regarding this situation, for example, a senior official at the town hall stated, “During evacuation drills, the elderly gather at the bottom of the stairs, but are unable to climb up to the evacuation site” (deputy mayor), and “It is impossible for residents in their 80s to evacuate other residents in their 80s.” (chairman of the Town Council). The participation rate of district residents in evacuation drills has declined from 70%–80% approximately 20 years ago to approximately 30% today. As stated by the former head of the Disaster Prevention and Safety Division, “The issue of evacuation for the elderly was not on the agenda 20 years ago,” and the recent demographic changes common to rural communities in remote areas, such as the aging of the population, have forced town authorities to reconsider their DRR measures.

The population of Nishiki district peaked at more than 4,300 in 1950 and has continued to decline annually, reaching one-third of its peak in 2020, with the five-year rate of decline increasing to approximately 10% since 1985. However, the number of households remained at approximately 1,000 from the 1950s to approximately 2000, but began to decline sharply after 2005, falling to approximately 750 households in 2020. Thus, the population decline could be attributed to the outflow of young people, with a concomitant reduction in household size and natural growth rate; however, the problem in recent years has been the rapid decline in the number of households. The percentage of elderly people rose sharply from 24% in 1995 to 55% in 2020 (the percentage of people aged 75 years and over rose from 10% to 32% during the same period), and the percentage of single-person households and households comprising only elderly couples rose from less than 10% in 1995 to more than 25% in 2020 (combined, they accounted for more than half of all households) (Fig. 5).

Note: The elderly population ratio and the ratio of households comprising only elderly population is not available before 1990. The number of households is not available for several years before 1990. Source: Population Census of Japan.

According to the interviews we conducted, knowledge and awareness of tsunami DRR among older adults remained at a high level. However, physical decline with age is undeniable and the disaster culture shared and inherited by families and communities is at risk.

Under these circumstances, in 2023, the town mayor proposed a plan to relocate elderly people who have difficulty evacuating to higher ground in advance. This project aims to construct eight town-owned rental houses for elderly households in need of support (20 to 30 houses in the end) on town-owned land 20 m above sea level (the original swamp land was reclaimed with construction debris from the highway), and provide a home-care and meal delivery services, a simple store, and a community bus stop, to be operational in 2028. Further, the project includes the relocation of the Senior Citizens Welfare Center, currently located in a low-lying area. According to the deputy mayor, this project aims to propose a model for livable living for the elderly and promote the integration of DRR and welfare for the elderly.

As described above, existing tsunami countermeasures in Nishiki district, which focus on emergency evacuation, have been forced to undergo revision owing to the weakening of the foundation of the community that supports them, and their effectiveness is now in doubt. Although the town authorities are aiming to improve the current situation by combining the physical expansion of structural facilities for DRR with the welfare of the elderly, the type of impact that this project will have on Nishiki district remains unclear. This is discussed in detail in the following sections.

3.1. Social Structure and DRR in Fishing Village

As described in Section 2, tsunami evacuation schemes in Nishiki were developed from the 1990s onward. This subsection examines community-based DRR in the area prior to that period by tracing longer-term changes in DRR practices in relation to local livelihoods (Table 1).

The Kumano-nada coastline, where Nishiki is located, is an excellent natural port. Although the area is prone to tsunamis and flooding, it has been inhabited since ancient times owing to its abundance of natural blessings.

Nishiki has one of the best fishing grounds in Japan, recording the highest catch of yellowtail during the 1930s. Despite extensive damage caused by the Tonankai earthquake, the residents of Nishiki rebuilt their lives and resumed fishing three months later ²⁸. After World War II, power boats became widespread and Nishiki’s fishing industry developed further. At its peak during the 1970s and the 1980s, the total value of fish landed at the Nishiki fishing port reached 3 billion yen, creating a boom in the Nishiki area (Fig. 6). There were more than a dozen bars, four public bathhouses, two movie theaters, and a billiard hall in the area.

Note: Based on documents provided by Nishiki Fisheries Cooperative Association.

Regarding social structure, Nishiki is an indigenous fishing village and a homogeneous area with overlapping local and blood ties. The history book of Nishiki-cho mentions this fact, stating that “almost everyone in the village is related to each other by blood” ²². The livelihoods of the people were almost exclusively fisheries, and the location was separated from the greater metropolitan area in terms of transportation conditions. Nishiki used to be a highly self-sufficient area.

In Nishiki, the fishing cooperative, agricultural cooperative, chamber of commerce and industry, Jichi-kai (community organization), and town office were regarded as the core organizations of the district, and these “Nishiki 5 union” formed a federation that managed the entire district (Fig. 7). Of these, fishing cooperatives were the most influential. At the peak of the fishing industry, 80% of the Nishiki residents were engaged in the fishing industry. Therefore, the head of the fishermen’s cooperative held the top position among the five organizations and was said to be “more powerful than the town mayor.” In addition, the proceeds from the fishing industry were used to fund public activities within the community. Nishiki’s mainstay fishery, the fixed-net fishery, was operated with funds invested by cooperative members (Oshiki-kumiai), and the proceeds from yellowtail catches were returned to the cooperative members in the form of shares (dividends). Among them, Jichi-kai was the major shareholder in Oshiki-kumiai. Jichi-kai in Nishiki was a community organization independent of the unit neighborhood association (Chonai-kai) and used dividends from the Oshiki-kumiai as funds for local events (festivals, etc.) and public works (simple water supply, etc.) in Nishiki. As described above, in the past, livelihoods and community organizations were integrated into Nishiki, and residents took the initiative in community management by using their financial resources. Thus, the role played by the town office was limited, and its status among “Nishiki 5 union” was relatively low.

DRR activities were also embedded in this organizational structure for livelihood and community activities. The leading DRR organization in Nishiki was the fire brigade. Nishiki’s fire brigade, with 400 members across three divisions, was regarded as one of the best in the prefecture. In addition to the regular fire brigade, fire brigade alumni organized a separate unit to support the fire brigade. Moreover, a separate relief group tasked with water rescue activities was organized, forming a broad social basis for community-based DRR. Young fishermen engaged in fire brigade activities were under the leadership of the fishing organization as members of the fishing boat fleet (haul net fishing) and had a strong sense of solidarity. Young fishermen were taken for granted as members of the fire brigade, and it was normal for them to concurrently engage in youth group activities (Seinen-dan). Thus, firemen were also in charge of local festivals and other events. Residents were able to ask young fishermen for help not only in the event of a disaster, but also if they had any problems. In this sense, DRR was integrated into livelihood and community organizations.

Self-help, a prerequisite for mutual aid, was also much more stable than it is today. As the fishing industry was hereditary and many households were multigenerational and lived together, measures for elderly people in need of assistance in the event of a disaster were not regarded as an issue requiring consideration.

Before the 1990s, awareness of the risk of a Nankai Trough earthquake was not as high in Nishiki, and evacuation drills were not conducted as they are today. However, according to interviews with residents, “things like today’s voluntary disaster management activities were carried out naturally in everyday life.”

3.2. Exogenous Development and Decline of Fishing Industry

However, Nishiki’s fishing industry gradually began to decline. As previously mentioned, Nishiki’s fish landings peaked during the 1970s and the 1980s, however, from the 1960s, the number of regular union members began to decline, and the percentage of associate members increased (Fig. 6). During the 1980s, the number of members of fishing cooperatives began to decline, a trend that continues today. The decline in the number of fishermen was not necessarily owing to low income. Certainly, the fishing industry, which deals with nature, has some income instability, but in Nishiki, during the high-growth period, fishermen’s income was reportedly much higher than that of ordinary civil servants. One factor that has had a significant impact on the fluctuations of the fishing industry in Nishiki is a series of exogenous developments, such as the plan to construct a nuclear power plant.

During the period of high economic growth in Mie Prefecture, the regional disparity in terms of population and financial capacity between industrial cities in the north and fishing villages in the south became pronounced. Against this backdrop, in 1963, the then-governor of Mie Prefecture proposed a plan to invite a nuclear power plant to Ashihama, located on the border between Kisei-cho (present-day Taiki-cho) and Nanto-cho (present-day Minami Ise-cho). In 1965, the Kumano-nada Coastal Development Plan was proposed to promote road and port development in the southern part of the prefecture, using compensation funds from the nuclear power plant project. The Ashihama nuclear power plant construction plan underwent complications and was finally withdrawn in 2000. Over the past 37 years, fishing villages along Kumano-nada have been at the mercy of development projects.

Kisei-cho’s decision to accept construction of the Ashihama nuclear power plant for financial reasons had the following effects on the fishing industry. First, fishing operations were restricted because of a site survey conducted by the Chubu Electric Power Company. Second, the large compensation payments guaranteed reasonable income even if the fishermen did not fish, which reduced their motivation to fish. Moreover, the town became increasingly dependent on compensation and donations from nuclear power plants for the development of roads, public facilities, and other infrastructures. Third, measures promoting the fishing industry were delayed. Owing to concerns about the impact of treated water (thermal wastewater) on fishing grounds after a nuclear power plant was constructed, the town authorities used compensation funds to formulate a plan to promote aquaculture, which led to a shift to yellowtail farming. However, yellowtail aquaculture was booming nationwide, resulting in overproduction and reduced fish prices. Further, fisheries cooperatives became increasingly dependent on compensation, and because they were left in a state of limbo, not knowing when the nuclear power plant would come online, they failed to take proactive measures to promote the fishing industry. Nishiki’s fishing industry fell behind other municipalities, such as Nanto-cho, which opposed nuclear power plant construction and actively promoted the development of the fishing industry. This long-term stagnation has caused the younger generation to leave the fishing industry. As Nishiki’s employment structure specializes in the fishing industry and alternative employment opportunities are scarce, many young people who left the fishing industry migrated out of the town ^29,30,31.

Even after the Ashihama nuclear power plant plan was withdrawn in 2000 after many complexities, Nishiki’s fishing industry continued to be under the influence of external development. Around the time that the nuclear power plant plan was canceled, a plan to build the Chubu International Airport emerged. The Chubu International Airport is an offshore airport that requires large amounts of reclaimed materials for construction. However, in the highly urbanized Aichi Prefecture, land-based sources of sediment supply were already limited. Dredging of marine sediment near the proposed airport site was also difficult because of environmental regulations; therefore, the aim was to procure reclamation materials exclusively from mountain soil in the hills of the southern Mie Prefecture ³². Kisei-cho was the largest supply area, and mountain soil from the hills was transported by a conveyor belt to the coast and then by ships to the planned airport site. This large-scale public works project created jobs in the construction industry in Kisei-cho, and brought large amounts of compensation to the fishing cooperative. However, the decline in the fishing industry and outflow of young people were further accelerated by the development project.

Furthermore, global warming has had a tremendous impact on the fishing industry in recent years, and fish landings have drastically decreased since 2018 owing to the significant meandering of the Kuroshio Current. To cope with such crises in the fishing industry, tourism fishing (running fishing boats and private accommodations) has been attempted in recent years. However, this is far from reviving the critical situation of the fishing industry.

3.3. Transformation of DRR

With the decline in the fishing industry and population outflow, there have been significant changes in the DRR in Nishiki, leading to a decline in community-based DRR.

First, the Nishiki 5 union was dissolved. A drastic decline in the number of fishery cooperative members and fish catches resulted in the loss of the financial support for the independent activities of the Nishiki 5 union. Consequently, the five unions lost their character as federated entities, and Nishiki’s cohesion and self-management weakened. Jichi-kai, which used to be the major shareholder of the Oshiki-kumiai and controlled the management of the district, also lost its role and was reorganized into a mere festival organization.

As the population declined and the number of small elderly households increased, the community’s neighborhood association activities also stagnated. As it is difficult to sustain community activities within the existing population, town authorities are now committed to using outside human resources such as Local Vitalization Cooperators and immigration measures. Although the inflow of migrants has brought a new impetus to residents’ lives, they are few and have not transformed population trends. The decline in population has been accompanied by the withdrawal of public and commercial services, which has significantly reduced the convenience of living in the area. The closure of Nishiki Junior High School in 2009 and Nishiki Elementary School in 2025 marked the deprivation of community functions.

Furthermore, these structural changes in Nishiki have led to changes in DRR mechanisms. As the number of fishermen declined, the fire brigade shrank from 400 members at its peak to approximately 60. The youth organization (Seinen-dan), which had once been inseparable from the fire brigade, was also disbanded. Firefighters’ alumni associations and relief groups were also dissolved. Consequently, the social basis of DRR activities in Nishiki has weakened. Taiki-cho authorities are currently promoting the development of voluntary disaster management organizations; however, Nishiki district is the only one in the town where such organizations have not yet been established. This is partly because Nishiki used to be able to cope with disasters without such organizations, but also because the unit neighborhood association (Chonai-kai), which is supposed to be the foundation for the voluntary disaster management organization, is not being operated properly owing to the excessive aging of the population.

The decline in community activities has been replaced by the growing presence of town offices (administrative management), which since the 1990s have taken the lead in disaster management and specialized in Nankai Trough earthquake countermeasures. As discussed in Section 2, various advanced efforts have been made to implement government-led countermeasures against hazards. However, DRR in Nishiki today is no longer related to local livelihoods and community organizations. Regarding financial resources, the construction of tsunami evacuation facilities and seawalls was made possible by reliance on compensation for external development and government subsidies (Fig. 8). Therefore, from a long-term perspective, the development of earthquake DRR countermeasures in Nishiki since the 1990s can be interpreted as a disconnection and transformation rather than the development of conventional community-based DRR.

4.1. Policy Integration of DRR and Welfare

As mentioned in Section 2, currently, in Nishiki, a plan has emerged to relocate the elderly who need assistance to higher ground in advance. Taiki-cho procured a project site on a hill at an elevation of approximately 20 m in the northern inland area of Nishiki district (red square in Fig. 2). The plan is to lay water pipes in this location and develop public housing for the elderly. The initial development will provide housing for 5–10 households, with expansion planned as needed.

Although the Nishiki tsunami evacuation scheme established in the 1990s was effective even in the event of the maximum-class Nankai Trough earthquake, it assumed that “healthy people who can evacuate quickly on their own” could do so. Under the current situation, where this premise has collapsed, it is reasonable to relocate elderly people who have difficulty evacuating to higher ground in advance as a tsunami evacuation countermeasure. In addition, as previously mentioned, the plan for relocating to higher ground includes welfare goals for the elderly and new community development. The plan is a model for the Act on Development of Areas Resilient to Tsunami Disasters in that it considers not only DRR but also community development.

Prior to the formulation of the upland relocation plan, town authorities conducted a face-to-face survey of all 517 residents aged 75 years and older, comprising 408 households residing within the town. The number of residents who responded to the survey was 296 from 213 households, with response rates of 57.3% and 51.2%, respectively. According to the results of this survey, 50.7% of the respondents expressed a desire to use elevated facilities. Town authorities assessed that the plan was largely supported and aimed to commence the construction of the project. One concern in the implementation of this project plan is securing financial resources. Relocation is expected to cost approximately 1 billion yen; however, the town’s finances are strained, with less than 20% of its own funds (in FY2023). Therefore, the feasibility of the project depends on national subsidies.

Although the aims of the town authorities for this plan are described above, the perceptions of elderly residents and other inhabitants of Nishiki regarding relocation to higher ground are examined through a detailed analysis of survey results and interviews.

4.2. Determinants of Relocation Orientation to Higher Ground

The simple tabulation results of the survey are summarized as follows. Almost all households are small elderly households with detached owner-occupied houses. 60.6% of the households are single-person households, and 39.0% are two-person households. Only 8.5% of the houses were earthquake-proofed. Of the respondents, 54.5% “have neighbors to help them when a disaster strikes,” indicating that nearly half of the respondents do not have neighbors to help them. However, 81.7% of the respondents “can evacuate to an evacuation shelter by themselves,” and the percentage of those who use welfare services is relatively low at 32.0%. Although more than 80% of the respondents said they could evacuate on their own, the aforementioned 50.7% desiring to use high-ground housing may reflect an uncertainty about their physical condition in the near future.

The plan aimed to move elderly individuals who have difficulty evacuating to higher ground in order to save lives. However, survey results revealed that those who have difficulty evacuating do not necessarily want to relocate to higher ground. Contrarily, such elderly people tend to be more reluctant to move (Fig. 9).

Analysis by district demonstrated that the percentage of respondents wishing to relocate to higher ground was not necessarily higher in areas where evacuation was difficult (Fig. 10).

Note: • indicates a high relocation preference rate, and ▲ indicates a low relocation preference rate. See Fig. 2 for the location of each district.

Indeed, Tsukiji–Suzaki, which has the highest relocation preference rate, is a reclaimed area on fragile ground and is the district with the highest risk in terms of tsunami inundation depth and arrival time. However, Wakaba–Sakae, which has a similarly high relocation preference rate, is furthest from the sea, and Wakaba, which is particularly hilly, is the district with the lowest tsunami risk. The high relocation preference rate in Wakaba–Sakae may not be because of the difficulty of evacuation, but rather may be related to the proximity of the relocation site to the current residence, making it easier to relocate (see Fig. 2 for the locations of each district).

Considering the districts with the lowest desired relocation rates, Okuide–Naka, which certainly has the lowest desired relocation rate, is located on a higher ground and has the lowest need for relocation. However, Hinode, which has the next lowest usage preference, is in the highest-risk area for tsunamis, like Tsukiji–Suzaki. According to interviews conducted in the area, this may be related to the fact that Hinode is a relatively recently developed neighborhood and housing is still new.

Second, related to the first point, residents’ intentions regarding relocation to a higher ground are not simply divided into two groups: those who wish to relocate and those who do not. The open-ended responses (84) confirmed the desire to relocate under various conditions. The most common condition was “it depends on the location.” The fact that the relocation site was decided top-down by the town authorities without consultation with the residents may have caused some dissension. In addition, although the planned relocation site was outside the tsunami inundation zone, the ground was fragile because it was created by reclaiming swamp land. Therefore, the residents did not have a satisfactory impression of the planned site, and during interviews, they expressed concerns that liquefaction would occur in the event of an earthquake. The next most common comment was “I would like to (relocate) if I could be with my neighbors.” This reflects the Nishiki’s indigenous nature. There were also opinions such as, “I can live here now, but if I become disabled (I would like to move).”

Reasons for not wanting to relocate were also diverse. Some of them were based on tsunami safety, such as “because I live on higher ground” or “because the evacuation site is closer,” but there were many other reasons as well. For example, “I don’t want to leave my familiar home.” This opinion is particularly prevalent among those who are very old and may be related to the previously noted tendency (Fig. 9) of those who have difficulty evacuating on their own to be less likely to wish to relocate. The purpose of relocating to higher ground is to save the lives of elderly people who have difficulty evacuating by themselves. However, this suggests a dilemma in that the elderly people are more attached to their current homes. Other reasons provided were “because I will be moving to a family member’s house elsewhere” and “because I cannot dispose of my house,” which are unrelated to the difficulties of the evacuation. As described above, while relocation to higher ground is the rationale for tsunami evacuation, the rationale for residents’ choices of residential location is much more diverse.

4.3. Disaster-Resilient Community Planning and its Challenges

The plan to relocate to higher ground in the Nishiki area was intended not only for tsunami evacuation but also for the welfare of the elderly and community development. Certainly, the plan to consolidate housing for the elderly in need of assistance at the relocated site and arrange simple stores and welfare facilities may contribute to improving the convenience of daily life. However, the following problems can be identified in this plan.

First, even if the elderly wish to relocate, it is not economically viable for them. As aforementioned, the elderly in Nishiki live in detached owner-occupied houses; however, if they wish to relocate, they must dispose of their owner-occupied houses. This is because, in addition to rent and relocation expenses for public housing, they will be forced to pay maintenance costs and property taxes if they retain their owner-occupied homes. However, they cannot expect their children to inherit their houses, and it is difficult for them to sell them. Regarding public subsidies, the Act on Development of Areas Resilient to Tsunami Disasters does not provide financial measures for purchasing private residential land for relocation. We noted earlier that some elderly respondents expressed the view that the reason they did not wish to relocate was because they could not dispose of their owner-occupied houses, a constraint arising from the above circumstances. Similar views were confirmed through field interviews.

1. “Economic problems are the primary issue. It is not that they do not want to move into upland housing, but the reality is that they cannot. It is difficult to decide whether to spend money on a tsunami that may or may not happen.” (from interview with fishery cooperative staff)

1. “During the Great East Japan Earthquake, the government bought residential land in tsunami-inundated areas. However, it is impossible for them to buy in advance. Then, I think it would be better if my house were also washed away by the tsunami.” (from interview with elderly resident)

Second, upland relocation will proceed based on individual choice. Thus, non-elderly and elderly residents who do not wish to relocate will remain in coastal areas. Consequently, unlike the Disaster Prevention and Group Relocation Promotion Project, which aims to relocate communities, this project may lead to community dissolution. As discussed, the elderly have a psychological resistance to such situations. Although the plan to relocate to higher ground may contribute to the formation of a welfare community at the relocation site, it may also divide the Nishiki district between residents living on higher ground and those remaining in coastal areas, weakening community cohesion.

Third, the plan to relocate the elderly to higher ground is not pre-disaster recovery planning. Pre-disaster recovery planning involves the advance preparation of post-disaster recovery projects ². For these reasons, in Nishiki, private houses remain on the beach, even after the plan to relocate to higher ground has been implemented. In the event of a maximum-class Nankai Trough earthquake, even if emergency evacuation is successful, the tsunami will wash away houses along the coast, making pre-disaster recovery planning for coastal areas an important challenge. However, at present, this point remains untouched, and even land for temporary housing is yet to be secured. The residents also expressed concerns regarding this issue.

1. “The town authorities should consider in advance, measures for shelters after a tsunami, not relocation. They should prepare places for people who survive after the disaster. If a disaster occurs, people have no choice but to relocate to the community. However, it is impossible to relocate collectively at this point.” (from interview with elderly resident)

Although land-use constraints are an important reason for the delay in pre-disaster recovery planning, a more fundamental reason is the difficulty in presenting a medium- to long-term vision for the town. If industry and job opportunities, which are prerequisites for the next generation of residents to continue living in an area, are not guaranteed, DRR countermeasures may lose their meaning.

1. “Even if we were able to evacuate from a tsunami, we would have no place to return to. We do not have a place to work. This is the fundamental problem this town faces.” (from interview with elderly resident)