Waveform-based source location method using a source parameter isolation strategy

We have developed a novel acoustic-wave-equation-based full-waveform source location method to locate microseismic events. With the acoustic-wave equation and source signature independent inversion strategy, source location parameters (hypocenter locations) can be isolated from others and can then be retrieved independently and accurately, even when the origin time and source signature are not correct. Based on the acoustic-wave equation, new Frechet derivatives of seismic waveforms with respect to the location parameters are derived to better accelerate the inversion process. To ease the cycle-skipping problem, a correlation is applied to select the best starting source positions. Some 2D and 3D numerical examples are presented to demonstrate the validity of our method. Compared with the waveform-based grid-search method, our method is effective in isolating the hypocenter locations from the source signature and origin time. The computational cost is nearly negligible compared with the waveform-based grid-search method. The robustness of our method is also tested for cases with inaccurate velocity models or using microseismic data with a signal-to-noise ratio of >= 0.2. Finally, field data are used to indicate the practical applicability of our method.