Models

The first step in developing General Earthquake Models will be to identify existing codes and models ranging in scale from tenths to tens of kilometers. We expect that GEM will encompass the dynamics and physics of individual faults, all the way through systems of faults. This includes fault rupture, the causes of rupture growth into a large earthquake, fault interactions on short and long time scales, and the role of rheology, heterogenity, random property, and noise. A centerpiece of early development will be a newly constructed fault-interaction model, to be built by a world-class team of parallel computing physical modelers using modern object/component paradigms. The planned adaptation of this hugely successful astrophysical N-body algorithm (``Fast Multipole Method'') to the implementation of stress Green's functions on interacting fault systems will represent a major advance, which when completed will provide a unique capability for modeling complex crustal dynamics. The expected computer requirements as the model matures will exceed 1 teraflop performance, which will become available through a number of computing centers during this time. Our approach ensures that these resources are well- spent, as the N-body algorithm is both accurate and efficient. In general, the friction models used for GEM will be based upon 1) laboratory experiments, such as the slip- weakening or rate-and-state models; 2) computationally simple models that capture in a simple way important aspects of frictional sliding, such as the classic Coulomb-Amontons law; or 3) statistical mechanics, in which the basic phenomenology of friction has been incorporated on coarse grained space-time scales.