Simple Models of the Earthquake Cycle Compared with Seismological Observations

9417700 Shaw This research involves the development and characterization of dynamical earthquake models which produce complex sequences of events from a frictional instability. Earthquakes are complex in many ways. The slip in an individual event, the distribution of sizes of events, when they occur, and where they occur, are just some of the complexities to understand. A fundamental open question is what is the source of the complexity. Recent work on simple models has shown that a remarkable degree of complexity can be generated by the self-organization of repeated ruptures on a fault. A particularly interesting class of models are deterministic, dynamical models in which all the complexity is generated by a frictional instability. There are two basic goals in this research. One is to develop models of earthquake faults that produce realistic behavior across the whole range of timescales in the earthquake cycle, from rupture, to foreshocks and aftershocks, to intermediate term changes, and on to steady state averages beyond the loading cycle. The second goal is to develop better ways of quantifying the complex behavior that is seen in the models; this helps to better understand what is happening in the models, to compare the behavior produced by different models, and most importantly, to compare with the behavior seen in the earth, and perhaps to suggest new ways of looking at the data from the earth. This research is a component of the National Earthquake Hazard Reduction Program. *** ??