Multi-hazard risk assessment and decision making
Cees J. van Westen, Stefan Greiving · 2017
The earth is shaped by endogenic processes, caused by forces from within the earth, resulting in hazardous events like earthquakes or volcanic eruptions, and exogenic processes, caused by forces related to the earth's atmosphere, hydrosphere, geosphere, biosphere and cryosphere and their interactions.Anthropogenic activities have had a very important influence on a number of these processes, especially in the last two hundred years, for instance through the increase of greenhouse gasses, leading to global warming, but also through dramatic changes in the land cover and land use, and overexploitation of scarce resources.The above mentioned processes from endogenic, exogenic and anthropogenic nature may lead to potentially catastrophic events, even in locations that may be far away.For instance earthquakes might trigger landslides which may lead to landslide-dammed lakes that may break out and cause flooding downstream.Or the dams of large reservoirs in mountains, constructed for hydropower, irrigation or drinking water, may fail under an earthquake or extreme rainfall event and cause a similar flood wave.These potentially harmful events are called hazards.They pose a level of threat to life, health, property, or environment.They may be classified in different ways, for instance according to the main origin of the hazard in geophysical, meteorological, hydrological, climatological, biological, extra-terrestrial and technological (See Table 2.1, from Guha-Sapir et al. 2016).Such classifications are always a bit arbitrary, and several hazard types could be grouped in different categories, e.g.landslides could be caused by earthquakes, extreme precipitation and human interventions.Hazards have a number of characteristics that should be understood in order to be able to assess and subsequently reduce their potential damage.Hazards with certain magnitudes may occur with certain frequencies, as small events may occur often, and large events seldom.In order to be able to establish a magnitude-frequency Chapter 2Multi-hazard risk assessment and decision making DroughtGlacial Lake outburst Wildfire Forest Fire, land fire (bush, pasture)