Rapid 3-D Earthquake Location using a Hybrid Global–Local Inversion Approach

A novel hybrid approach to earthquake location is proposed which uses a combined coarse global search and fine local inversion with a minimum search routine. The method exploits the advantages of network ray tracing and robust formulation of the Fréchet derivatives to simultaneously update all sampled initial source parameters in the solution space to determine the best solution. Synthetic examples, involving a three-dimensional (3-D) complex velocity model and a challenging source–receiver layout, are used to demonstrate the advantages over direct grid search algorithms in terms of solution accuracy, computational efficiency, and sensitivity to noise. Therefore, this is a promising scheme for earthquake early warning, tsunami early warning, rapid hazard assessment, and emergency response after strong earthquake occurrence.