Mapping Earthquake Risk of the World

Abstract

In the program of Global Natural Disaster Hotspots, jointly conducted by Columbia University and the World Bank, mortality rate and economic loss rate caused by earthquake disaster are calculated as vulnerability coefficient based on mortality and economic losses in the historical earthquake records. Then the vulnerability coefficient is adjusted by earthquake density which is measured by earthquake fre- quency to estimate mortality risk and economic loss risk in the world (Dilley et al. 2005). In the program of Global Risk and Vulnerability Index Trends per Year (GRAVITY), hosted by the United Nations Environment Programme (UNEP)/Euro- pean Global Information Resource Database, the vulnerability of earthquake is calculated based on hazard intensity, death toll, and so on in the historical earthquake records and combined with other economic indicators to establish loss function, to estimate annual average expected losses (Peduzzi et al. 2009). These two programs are the most influential natural disaster risk assessment projects. However, in the Global Natural Disaster Hotspots, loss rate of all previous earthquakes in the same region is used to represent both hazard and vulnerability, which cannot reflect spatial differ- ences of risk, caused by spatial distribution differences of hazard and vulnerability. Therefore the programs are only be used for risk assessment at national level. The assessment results of GRAVITY are also at national level, which cannot demonstrate the risk differences within the country and region. Meanwhile, both programs take GDP as exposure for the assessment of economic losses, which describes economic flow. However, the earthquake imposes direct impact on economic stocks, which is quite different from economic flow. Therefore, building vulnerability table at national scale and possibility of mortality caused by building collapse shall be taken into consideration to construct population vulner- ability table. Combined with population density data and earthquake intensity, world earthquake mortality risk can be assessed. Meanwhile, social wealth shall be taken as social and economic exposure instead of GDP to assess world earthquake economic loss risk. Based on the above con- ceptions, the earthquake risk of the world is reassessed and mapped in this study at grid, comparable-geographic unit and national levels.