ESTIMATING THE SIZE AND EXTENT OF FUTURE EARTHQUAKE RUPTURES ON MAPPED FAULTS

The foundation of seismic hazard analysis today generally rests on a map of active faults. To that map the analyst is required to make estimates of the size of future earthquakes expected on the faults. The parameters of size include coseismic slip, the rupture length, magnitude and seismic moment. There now exist about 3 dozen historical earthquakes for which investigators have constructed maps of earthquake rupture traces accompanied by descriptions of coseismic slip observed along fault strike. Here I use that data base to (1) develop empirical regressions relating moment, magnitude and rupture length, (2) characterize the shape and complexity of surface slip distributions and estimate surface rupture hazard, (3) establish the relationship of earthquake epicenters to the shape of earthquake slip distributions, and (4) show how measures of fault geometry provide a preliminary statistical basis for predicting the endpoints of earthquake ruptures. Within this framework I will also point to various implications of the data set to our understanding of the physics of the earthquake source.