Types, Definition and Classification of Natural Disasters and Threat Level

In this chapter, various types of natural disasters, their classifications and threat levels are considered. Natural disasters vary widely in predictability and impact. A widely used natural disaster typology has been considered as the starting point for covering natural disaster classifications and their threat levels. Threat levels have been analysed from two perspectives – social and economic – to identify their impacts. The threat levels associated with social and economic impacts of natural disasters can be significantly high where a large number of people are affected; and total economic losses can range in hundreds of billions every year from the damages caused by natural disasters. In terms of occurrences, climate-related disasters also dominate the picture, accounting for 91% of all 7255 major recorded events between 1998 and 2017. Floods, 43.4%, and storms, 28.2%, are the two most frequently occurring disasters. It is found based on a detailed literature review that social and economic impacts vary, not only for specific disasters but also by region. Fatalities, loss of livelihoods and displacement from natural disasters are most prominent in Asia Pacific. Threat levels are more pronounced in Asia Pacific regions due to resource constraints and lack of proper communications and adequate response measures to reduce impacts. This is also an extremely serious threat issue as two-third of the world population – an estimated 6.3 billion people – live in Asia and Africa. Asia, despite its relatively lower level of urbanisation, is home to 54% of the world’s urban population. Therefore, it is recommended in this chapter that global collaborative efforts (including implementation of resilience measures) be undertaken to address natural disasters and the related threats in a timely and efficient manner, resulting in least negative economic and social impacts.