robabilistic microearthquake location for reservoir monitoring

Accurately locating microseismic events can be used to monitor fluid migration during reservoir production and hydrofracturing operations. This is usually done with sparse networks of seismic sensors located in boreholes or with denser surface arrays. The data used for microearthquake monitoring are corrupted by noise, which reduces the signal-to-noise ratio to values as low as 0.1. Monitoring methods based on traveltime picking of various wave modes P or S cannot deal with this level of noise and require extensive user interaction. An alternative class of methods uses time reversal to focus microearthquake information at the source position. These methods can handle noisier signals because they do not rely on event picking or recorded seismograms, but the methods are also costlier to run and still require picking locations where wavefields focus. We advocate the time-reversal technique within the general framework of Bayesian inversion. Given an assumption about the possible locations of microearthquakes, we use recorded data to evaluate the feasibility