The Ring of Fire in the Asian region is considered to be the area on earth most frequently hit by earthquake disasters and it is located in the basin of the Pacific Ocean. Earthquakes are widely recognized as unpredictable and infrequent disasters that have serious impacts on human settlements, including death and injury, property loss and damage, economic depression, and the breakdown of essential facilities [1
]. Structural engineering measures have been the major way to cope with earthquake disasters, for example by seismic strengthening and the seismic improvement of structures. However, loss of life and building damage are possible whenever development is allowed in hazardous seismic areas if the magnitude of the disaster is at or below the design standard incorporated into the building codes and structural work [3
]. In fact, the threats posed in a given area by future earthquakes with a magnitude larger than that experienced in the past create uncertainty about the ability to mitigate earthquakes’ impacts to acceptable levels using only engineering or construction measures.
Since the 1980s, nonstructural measures in both urban planning and architecture have moved far beyond the retrofitting of seismic damage, and seismic resistance has received much attention worldwide [6
]. Land use planning is one of the nonstructural measures used to eliminate risk by steering future development away from risk areas and by enforcing particular structural engineering practices for that part of the built environment exposed to a relatively high earthquake risk. Common approaches to earthquake loss mitigation include land use planning policies, land acquisition programs, taxation policies, and other strategies in which certain standards, codes, or design requirements are applied only to specific sites known to be particularly hazardous [9
]. Nevertheless, arguments have arisen for applying land use planning in earthquake risk areas. Indeed, land use planning is a proactive measure that can be taken to avoid or minimize losses.
The zoning regulation in high earthquake risk areas might impact private land owners and developers given that a relatively higher risk is accompanied by a higher construction cost [5
]. A survey demonstrated that residents were willing to pay $
6000 to relocate outward from a fault zone area [10
]. Other studies suggest that property values are relatively low in earthquake risk areas [11
]. Most previous studies regarding disasters in the hedonic house price literature indicate that proximity to a risk source has a negative effect on housing value [15
]. However, a contrasting finding demonstrates that locations within fault zones are not disadvantaged for house buying and loan decisions. Another hedonic price study indicates that a surface fault rupture has little impact on the operation of the housing market [16
]. A more recent study reports that a legal fault zone area limits the building area and further provides more open space, and such a land use type increases not only the amenity but also the house price in fault zone areas [17
In Taiwan, the Chelungpu fault slipped, causing the 921 Chi-Chi Earthquake, in 1999. In this earthquake, nearly 2500 people were killed, 11,000 people were injured, and $12 billion worth of damage was incurred. Because more damaged buildings were clustered along the Chelungpu fault line, the Construction and Planning Agency (CPA) of the Ministry of the Interior announced a 50 m temporary prohibited zone along each side of the Chelungpu fault, and the prohibition period continued until the end of 1999. After a more accurate geologic map (1/1000) had been created by the Ministry of Science and Technology in 2000, the CPA announced a 15 m fault zone on each side of the Chelungpu fault, and the zoning regulation continued until the end of 2001. Owing to the serious damage experienced along the Chelungpu fault by urban planning areas, local planning agencies revised the urban planning maps and zoning regulations in the fault zone area 15 m on each side of the Chelungpu fault. Currently, the Chelungpu fault is the only fault that has a fault zone regulation in the urban planning area in Taiwan. Within the regulated fault zone area, building is only allowed for residential use, and the building height should be lower than seven meters. There is no such zoning regulation in non-urban planning areas because the general restriction period placed on the fault zone area only continued until the end of 2001.
In Taiwan, there are forty-one active faults and other earthquake-prone areas, including areas with soil liquefaction and landslides. The argument of whether to apply land use planning in earthquake-prone areas continues worldwide. Therefore, the principle focus of this study is an exploration of the patterns, distributions, and trends of land use and property transactions in geographic information systems. The spatial autocorrelation coefficient can combine the characteristics of both Pearson’s correlation coefficient and Moran’s I
to evaluate the spatial characteristic of land use and property transactions. In Taiwan, a distance of 15 m from each side of the fault line has been regulated as a fault zone restricted land use area for over ten years. The assessment of such zoning regulations is important not only to identify the impact on both land use and property transactions but also to determine its effectiveness. Therefore, the spatial cluster of land use change and property transaction value within and outside the regulated fault zone is explored to discuss the impacts, or lack thereof, of zoning regulations in fault zones. In addition, the effectiveness of such zoning regulations will be investigated. The data and methodology are illustrated in Section 2
, including the study area, data description, and spatial autocorrelation coefficient. In the next section, the results for the spatial characteristics of land use change and property transactions are discussed. A discussion of the field investigations exploring the effectiveness of zoning regulation in the fault zone area follows in Section 4
. The paper then concludes with findings and implications in Section 5
Land use planning is one nonstructural measure used to eliminate risk by steering future development away from a risk area and by enforcing particular measures for the existing built environment according to the disaster risk. Nevertheless, various arguments have arisen around applying land use planning in earthquake risk areas. Among these arguments, the announcement of land use planning in earthquake risk areas is a type of disaster risk information disclosure and might impact real estate development willingness or property values. Although land use planning in earthquake risk areas might not impact real estate development willingness, some studies have determined that real estate value in earthquake risk areas is lower than that in non-earthquake risk areas [11
This study empirically examined how land use planning in an earthquake risk area has been reflected in land development and property value since 2002. The results demonstrate that, although “continue building use” parcels in different time periods are located to the west of the fault zone area, the later ones tend to be built close to Chelungpu fault. By contrast, “become building use” parcels in the earlier time period are located outward from the “continue building use” parcels, whereas later they are located on or nearby the fault zone area. According to the property transaction data, the buildings built before the 921 Chi-Chi Earthquake are located on or nearby the fault zone area in the southern portion, whereas the most recently built buildings are located on or close to the fault zone area in the mid and northern portions.
Owing to the serious damage along Chelungpu fault, local planning agencies revised the urban planning maps and zoning regulation in the fault zone area along each side of Chelungpu fault. Therefore, this paper investigates land use along the fault zone area in both urban planning areas and non-urban planning areas (zoning regulation is regulated in the urban planning area only). On the basis of the zoning regulation in the fault zone area in the urban planning area, the building ratio must be less than 50%, while the floor area ratio should be less than 180%. The only building use type in the fault zone area is residential. In addition, the building height should be less than 7 m.
In the urban planning area, the land use investigation shows that newly constructed buildings (some buildings are even for sale) in the fault zone area are consistent with the zoning regulation, including being residential-only and less than 7 m in height (see Figure 7
). Furthermore, residential use is the major land use type within the fault zone area. The zoning regulation is a type of earthquake risk information disclosure, and, according to previous studies, such disclosure might lead to some type of passive attitude toward land use development and may even have a price impact on property transactions. However, the newly constructed buildings with legal building licenses demonstrate the continued willingness to reside within a fault zone area with an improved seismic structure.
The 15 m restriction zone on each side of Chelungpu fault was continued until the end of 2001, after which there were no zoning regulations in the non-urban planning area. The land use investigation in the non-urban planning area indicates that there are newly constructed buildings close to the fault line as well. The building certificate licenses demonstrate that the building height is relatively higher than that of buildings in the urban planning area (see Figure 8
). In addition, the height of some buildings in reality is inconsistent with that on the building certificate. In addition to residential use, multiple mixed uses are clustered near or on the fault zone area, which could lead to major damage during serious earthquakes.
This paper empirically examined how zoning regulations in earthquake risk areas have been reflected in land use and property transactions since 2002. The results demonstrate that “become building use” parcels in the earlier time period (1995–2008) are located outward from “continue building use” parcels, whereas the later “become building use” parcels (2008–2014) are even located on or nearby the fault zone area (see Figure 5
c,d). In addition, buildings built before the 921 Chi-Chi Earthquake located in or near the fault zone area are located in the southern portion, whereas the most recently constructed buildings are located in or close to the fault zone area in the middle and northern portions (see Figure 6
There has been zoning regulation in the fault zone area in the urban planning area since 2002, but such zoning regulation was only implemented until the end of 2001 in the non-urban planning area. There are newly constructed buildings in both the urban planning and the non-urban planning areas. Most newly built buildings in the urban planning area comply with the zoning regulation with legal building certificates. By contrast, some newly built buildings in the non-urban planning area are relatively higher and see more intensive use near or in the fault zone area. Comparing the building use in the urban planning and non-urban planning areas, the lower height and less intensive use complying with zoning regulation in the urban planning area might help mitigate the potential impact of earthquakes when the fault slips in the future.
Arguments have arisen about applying land use planning to earthquake risk areas, as this serves as a type of disaster risk information disclosure that might impact the willingness to develop land or property value. However, the results indicate that the most recently constructed buildings are located in or close to the fault zone area and have relative higher property prices. In fact, the effects on housing value might vary because of many other factors, such as the house itself, the housing market, the residents’ perception of the hazard risk, etc. Therefore, it is necessary to discuss the factors affecting those who are risk-averse or risk-inclined. A more thorough assessment of land use planning in earthquake risk areas should consider the risk perception and adaptation behavior of households.