# An Overview of GIS-Based Assessment and Mapping of Mining-Induced Subsidence
## 2 GIS-Based Engineering Geology Maps  
An engineering geological map refers to a type of a map that provides a generalized representation of all the key components of a geological environment in land-use planning and in the design, construction, and maintenance as applied to civil and mining engineering [15]. More recently, [PERSON] and [PERSON] [16] reported that geological engineering maps present the geological and geotechnical information for land-use planning, development, regeneration, and conservation, and to plan, construct, and maintain buildings, engineering structures, and infrastructure. According to [PERSON] et al. [17], engineering geology maps can be classified into inventory maps, susceptibility maps, hazard maps, and risk maps, as listed in Table 1.  
In terms of mine subsidence, an inventory map shows the location, type, abundance, activity, and date of past subsidence [18; 19]. In the simplest case, this map type only shows the location of past subsidence. Because the past and present are keys to the future, an inventory map of the historical data can be used to predict the probability of future subsidence or to validate the prediction accuracy of the generated subsidence susceptibility map. Accordingly, the inventory map is the first step in any mitigation program. However, because an inventory map is mainly compiled through remote sensing observation technologies or field surveys, it is not considered a GIS analysis. Thus, published literature on inventory maps is excluded from this study.  
Figure 1: Photos of representative mining-induced subsidence occurrence.  
The basic concept of subsidence susceptibility includes the spatial distribution of factors related to instability processes; this concept is used for determining zones of subsidence vulnerable areas without any temporal implication. A subsidence susceptibility map shows where subsidence may occur via the ranks of ground stability of an area in categories that range from stable to unstable. Subsidence susceptibility has also been considered as an expression of relative hazard.  
Subsidence hazard is defined as the probability of occurrence within a specified period and within a given area of a potentially damaging phenomenon [20]. The term 'Hazard' in this instance is different from what we commonly use for the word \"hazard or in danger\". The concept of a subsidence susceptibility map is different from that of a subsidence hazard map in that the latter includes zonations showing the annual probability (likelihood) of subsidence occurring throughout an area.  
Although several different definitions of the term risk exist, one of the most frequently adopted definitions is presented by [PERSON] [20] as the expected number of lives lost, persons injured, damage to property, and disruption of economic activity caused by a specific damaging phenomenon for a given area and reference period. From this standpoint, it can be said that a subsidence risk map shows the expected annual cost of subsidence damage throughout the affected area and combines the probability information from a subsidence hazard map with an analysis of all possible consequences such as property damage, casualties, and loss of service [21]. The estimation of the risk associated with subsidence events can be computed (quantified) by multiplying the subsidence hazard index by the exposure intensity index and vulnerability index [22].