Scientific Framework

GEM will provide state-of-the-art open source software and databases as a necessary basis for reliably mapping, monitoring, and communicating earthquake risk.

Different types of software and tools will be available, adapted to the needs of various stakeholder groups. In order to achieve this, implementation of the model is based on a combination of national, regional and global elements, and integrates developments on the forefront of scientific and engineering knowledge of earthquakes as well as IT processes and infrastructure.

The GEM scientific framework serves as the underlying basis for constructing the model, and is organised in three principal integrated modules:

Within GEM, seismic risk is defined as a product of seismic hazard (the probability of levels of ground shaking, resulting from earthquakes, within a given time span), seismic vulnerability (the probability of loss given a level of ground shaking), and exposure (the elements at risk, mainly buildings, critical infrastructure and humans). Risk tells us something about the extent of loss (damage, fatalities, casualties) that can be expected in a given location in the world. Risk can therefore be high in an area without significant probabilities of ground shaking, because it has an older, more vulnerable and densely populated building stock, and lower in an area with high levels of seismicity, but with well constructed structures that are sparsely inhabited.

Earthquakes however have an impact that goes beyond physical damage or casualties. Earthquakes can severely damage the economy and influence society and social well-being. Therefore, GEM will include innovative methods for analysis and evaluation of the impacts of earthquakes on the short, medium and long term, on local and global scales. There will also be applications that build upon the model, such as a tool for cost-benefit analysis, allowing users to understand what effect certain mitigation actions, strengthening of the building stock for example, will have on the risk. Insight into earthquake effects over time will directly support decisions on short term needs after an event (relief, shelter), medium-term needs (recovery and reconstruction) and long term needs related to policies on risk mitigation.