General Earthquake Models represent a coordinated effort within the United States' scientific community to develop highly realistic earthquake models for use in understanding the physics of earthquakes. GEM will develop a set of tools for use on high performance computers to simulate earthquake processes. By developing these tools such that the gaps between small and large scale models are bridged we will effectively develop a ``numerical laboratory''. Investigating the physics of earthquakes can then be approached as an ``experimental science'' that will complement existing observational and theoretical approaches. GEM will allow us to test for consistency between models, to explore the effects of friction, segmentation, loading due to plate motion, boundary conditions, random events, and the neglect of sub-grid-scale processes, all of which will result in more physically realistic models, further advancing our understanding of earthquakes.
Data will be assimilated to validate the models, and through GEM, diverse data sets can be related to each other by a process known as ``Model-Based Inference''. Data collection and archiving will not be a part of GEM, however we anticipate that through GEM data needs will be identified. This will help to drive data collection efforts in a variety of disciplines. We plan to use the GEM simulations to develop new space-time pattern recognition and analysis techniques. These may very likely lead to the development of forecasting and prediction methodologies for the reduction of earthquake hazard to lives and property.