Resolving Fault Plane Ambiguity for Small Earthquakes

We have developed an automated procedure to resolve fault-plane ambiguity for small to medium-sized earthquakes (2.5 ≤ ML ≤ 5) using synthetic Green's tensors computed in a 3-D earth structure model and applied this procedure to 35 earthquakes in the Los Angeles area. For 69% of the events, we resolved fault plane ambiguity of our CMT solutions at 70% or higher probability. For some earthquakes, the fault planes selected by our automated procedure were confirmed by the distributions of relocated aftershock hypocentres. In regions where there are no precisely relocated aftershocks or for earthquakes with few aftershocks, we expect our method to provide the most convenient means for resolving fault plane ambiguity. Our procedure does not rely on detecting directivity effects; therefore it is applicable to any types of earthquakes.