Abstract

How do seismic moment and fracture energy partition spatially on faults? This question can only be answered by incorporating observed heterogeneous fault frictional properties, such as breakdown distance (), ie, the total sliding distance between peak and sliding shear friction on each point on the fault. We assume to be heterogeneous and consistent with a spatial fractal process and perform spontaneous dynamic rupture simulations for three cases: i) both and the initial shear stress () are heterogeneous and proportional, ii) and are heterogeneous and inversely proportional, and iii) the case where is homogeneous and is heterogeneous. Our findings show that by performing small changes on the average, the rupture process shows evidence of self-arrested and runaway rupture, ie, ruptures that reach the boundaries of the fault model. In addition, selfarrested ruptures characterized by heterogeneous fractal and show agreements with observed spatial seismic moment release () of real earthquakes, such that asperity zones, represent~ 25% of the total ruptured area, with~ 45% of the total seismic moment. For self-arrested ruptures, the average dynamic shear stress drop within the asperities is~ 4 to 10 MPa. Outside these asperities, the average stress drop is lower than 6 MPa. In contrast runaway ruptures, release~ 45% of the total seismic moment in a much smaller area of~ 10%. These observations are of importance to capture source rupture characteristics for ground motion simulation purposes.