The term vulnerability is used in various disciplines with slightly different definitions. For example, in computer science the term refers to a specific weakness in a system or network, while in ecology, it is the opposite of resilience. The word vulnerability is derived from Latin and means “susceptibility”.
In the context of our natural hazard analysis, it concerns the question of the specific sensitivity of an object to the impact of natural hazards. The easiest way to show how differently sensitive objects can be is to use extreme examples: if a depot where concrete railway sleepers are stored is hit by a heavy hailstorm … nothing happens. However, if the same hailstorm hits an uncovered car park with brand-new cars stored for further transport, the damage and the associated effort are enormous.
The natural hazard risk analysis with K.A.R.L. is divided into two parts: on one hand, the natural hazard models in K.A.R.L. provide an assessment of the hazard situation (e.g., in a 100-year flood event, the water level at the site is one meter). On the other hand, together with the vulnerability and the value of the site the risk is calculated.
The vulnerabilities to the various natural hazards are each represented as a curve. Such a set of vulnerability curves currently consists of six curves for the natural hazards earthquake, flood, tsunami/storm surge, storm/tornado and hail (Fig. 1). In each case, a certain level of impact strength (i.e., intensity of an event) is set against an assumed percentage of damage. In the case of volcanism, the distance to the volcano replaces the impact intensity, as it can be assumed, regardless of the type of volcano considered, that the damage decreases with increasing distance to the volcano.
The vulnerability can vary greatly depending on the natural hazard and the object under investigation. The more accurate the desired result, the more carefully the vulnerability curves must be defined. It would be conceptually incorrect to assume a uniform vulnerability for all objects. On the other hand, an individual vulnerability for each object of study, considering every detail, is not practical. Therefore, in practice, it is beneficial to create categories (clusters) of similar vulnerability, each with its own set of vulnerability curves.
When determining the vulnerability of a building to various natural hazards, we essentially use two methods, which can also be combined in practical application:
Fig. 1: Example of vulnerability curves.
When determining vulnerability through expert assessment, the question must be asked for each natural hazard as to what level of damage would be expected for each level of impact. While individual cases provide some guidance, the focus is not on extreme, individual events but rather on the statistical expectation. For example, we do not consider the case in which a particularly torrential flood completely washes out a building and causes it to collapse, but rather the average case of standing or slowly flowing waters.
The percentage damage figures always refer to the restoration value, i.e., the actual damage to property. Answering the following questions has proven to be helpful:
Fig. 2: Simplified illustration to explain the development of a vulnerability curve.
The estimation of the possible damage to the different parts of the building and their share in the restoration value of the building then lead to a complete vulnerability curve for flooding (Fig. 2).
A similar approach is used to develop the curves for the other natural hazards.
The separation of the risk analysis into natural hazard analysis and vulnerability assessment ensures a high degree of transparency of the results for the client, who can always understand how a result is composed.
Your building does not fit into any of our vulnerability clusters? We are happy to advise you in creating your specific vulnerability and are available for any questions.
In the context of our natural hazard analysis, it concerns the question of the specific sensitivity of an object to the impact of natural hazards. The easiest way to show how differently sensitive objects can be is to use extreme examples: if a depot where concrete railway sleepers are stored is hit by a heavy hailstorm … nothing happens. However, if the same hailstorm hits an uncovered car park with brand-new cars stored for further transport, the damage and the associated effort are enormous.
Vulnerabilities are an important component of the K.A.R.L.® natural hazard analysis
The vulnerability of the object under investigation is an important component of the risk analysis with K.A.R.L. (Köln.Assekuranz.Risiko Lösung). The extent of the damage that can be expected if a specific event occurs depends on the vulnerability.The natural hazard risk analysis with K.A.R.L. is divided into two parts: on one hand, the natural hazard models in K.A.R.L. provide an assessment of the hazard situation (e.g., in a 100-year flood event, the water level at the site is one meter). On the other hand, together with the vulnerability and the value of the site the risk is calculated.
The vulnerabilities to the various natural hazards are each represented as a curve. Such a set of vulnerability curves currently consists of six curves for the natural hazards earthquake, flood, tsunami/storm surge, storm/tornado and hail (Fig. 1). In each case, a certain level of impact strength (i.e., intensity of an event) is set against an assumed percentage of damage. In the case of volcanism, the distance to the volcano replaces the impact intensity, as it can be assumed, regardless of the type of volcano considered, that the damage decreases with increasing distance to the volcano.
The vulnerability can vary greatly depending on the natural hazard and the object under investigation. The more accurate the desired result, the more carefully the vulnerability curves must be defined. It would be conceptually incorrect to assume a uniform vulnerability for all objects. On the other hand, an individual vulnerability for each object of study, considering every detail, is not practical. Therefore, in practice, it is beneficial to create categories (clusters) of similar vulnerability, each with its own set of vulnerability curves.
Building details
This approach was exactly applied to create the building vulnerabilities used in K.A.R.L.. In cooperation with the Association of German Pfandbrief Banks (vdp), a classification into currently ten clusters was made, covering a wide variety of building types from single-family houses, office buildings, and shopping centers to undeveloped land. A complete set of vulnerability curves was developed for each of these ten clusters.When determining the vulnerability of a building to various natural hazards, we essentially use two methods, which can also be combined in practical application:
- the determination of vulnerabilities through expert assessment
- the determination through the analysis of past damage data
Fig. 1: Example of vulnerability curves.
When determining vulnerability through expert assessment, the question must be asked for each natural hazard as to what level of damage would be expected for each level of impact. While individual cases provide some guidance, the focus is not on extreme, individual events but rather on the statistical expectation. For example, we do not consider the case in which a particularly torrential flood completely washes out a building and causes it to collapse, but rather the average case of standing or slowly flowing waters.
The percentage damage figures always refer to the restoration value, i.e., the actual damage to property. Answering the following questions has proven to be helpful:
- At what level of impact does the first significant damage occur, meaning how long does the damage remain at 0%?
- Is 100% damage even conceivable and if not, what is the maximum possible damage?
- From an expert perspective, is there an opinion on how the curve should run between the two extreme points based on the answer of the first two questions? Are there example cases that support these assumptions?
An example
For instance, when examining an office building in the size category of 3-7 floors and considering the impact of a flood, the damage largely depends on the height water:- Depending on the construction method, there is usually a small height (defined here as 10 cm), below which water cannot yet or cannot significantly enter the building. This results in no or only very minor damages, such as necessary cleaning.
- As soon as the water enters the building in significant amounts, the extent of the damage gradually increases (Fig. 2): Floor coverings, plaster, electrical installations, the technical building equipment (TGA) are increasingly affected and can be damaged or destroyed.
Fig. 2: Simplified illustration to explain the development of a vulnerability curve.
The estimation of the possible damage to the different parts of the building and their share in the restoration value of the building then lead to a complete vulnerability curve for flooding (Fig. 2).
A similar approach is used to develop the curves for the other natural hazards.
The decisive degree of damage
Not every risk analysis is focused on the damage to the object itself. Therefore, the perspective of the observer is crucial when creating vulnerabilities. For example, if an owner wants to carry out a risk analysis for his building, he faces a continuously increasing burden. The owner suffers financial loss even if the impact on the property is minor. The situation is different when conducting an analysis regarding a potential business interruption. Here, the primary question is not about material damage but rather: When does production need to be halted? The focus is thus on larger damages or potential total losses. Therefore, the vulnerability curve for the same object only starts to rise at a stronger intensity level.Conclusion
A carefully prepared set of vulnerability curves is an important prerequisite for a successful risk analysis. When creating such curve sets, it is important to form categories or clusters to keep the complexity manageable.The separation of the risk analysis into natural hazard analysis and vulnerability assessment ensures a high degree of transparency of the results for the client, who can always understand how a result is composed.
Your building does not fit into any of our vulnerability clusters? We are happy to advise you in creating your specific vulnerability and are available for any questions.
