LAUSR

In passive source seismology, seismic interferometry typically refers to the cross-correlation of ambient noise to construct an estimate of the Green's function between sensors. The presence of persistent natural and/or anthropogenic sources can bias or prevent the retrieval of these estimated Green's functions. Here we show how these strong persistent sources can be used to measure small changes in the medium between a source and either (or both) source-sensor pairs. The method relies on localizing the sources and using this information to identify and select cross-correlation functions for each source of interest. We illustrate this method by monitoring growth of a block cave at an underground mine using three nearly continuously operating ore-crushers which dominate the wavefield. This technique should work equally well in natural environments using sources such as volcanic tremor, hydrothermal bubble cavitation and microseisms.