Risk and vulnerability
Without the natural processes of earthquakes, volcanic eruptions, landslides and floods, the Earth’s surface would not have its spectacular shape (Figure 1). However, those mountain building and mountain degrading processes can also represent threats to society, especially if the energy of individual events is high. These processes can interfere with the normal flow of society and cause destruction, injury and also death (Figure 2). Surprisingly, several advanced cultures throughout history have developed in areas where those natural threats have been highest. It seems, therefore, that adaptation to a steadily changing world necessitates innovation and mobility and hence forms a strong society.
In the science of natural hazards, we call the natural processes with damaging energy a threat. The hazard itself includes the quantification of the energy of an event, the estimation of which area can be affected and the likelihood of its occurrence. A map showing those parameters is called a landslide, earthquake or volcano hazard map. To produce such a map requires a profound understanding of the natural processes and the materials involved. That is obtained only through studying in natural sciences and years of experience as a specialist working in a team. In addition, it is necessary to have a good overview of the distribution of earth surface materials, which can be acquired through geological mapping. This is costly as it requires field visits by the expert or mapping using costly remote sensing data obtained from satellite or airplane. In order to decide where it is necessary to expend the time and money to produce a hazard map, a susceptibility map is produced first. Those maps normally do not indicate a study of the likelihood of an event or its energy but only the area that might be affected, and do not require field mapping
Vulnerability and risk
If the planet Earth was not inhabited by humans, no one would care about the natural processes forming the landscape. It is the interplay of natural processes with human activity within the natural space that causes exposure, as the natural threats can disturb our life by destroying property and infrastructure and agricultural land[KS3] , and causing injury, health problems and even loss of life. We call this the vulnerability of society. When we estimate vulnerability, we also include reduction of productivity and other economic losses such as interruption of touristic activity and sudden changes to the environment. Risk is therefore seen as the hazard of a natural threat that interacts with the vulnerability of society.
The risk of natural hazards can be reduced by either preventing natural threats (e.g. stabilization of slopes) or by mitigating the negative consequences out of natural threats (e.g. imposing strong building standards, restricting building in hazard zones, early warning and evacuation). Both depend on understanding the hazard in detail (Figure 1). The coping capacity of society includes prevention and mitigation but also the capacity of society to rebuild itself after the impact of a natural event. The coping capacity can be improved by, for example, learning from past events and ensuring in advance that there are adequate resources to guarantee a fast rebuild.