Conclusions

Helioseismology validates a long-standing geophysical conjecture that the cross-correlation of noise traces may provide impulse response seismograms.

Additionally, we have shown that combining one-dimensional Kolmogoroff spectral factorization algorithms with helical boundary conditions allows us to calculate the acoustic impulse response an order of magnitude faster than cross-correlation in either (t,x,y) or $(\omega,x,y)$.

This is all very interesting, but our sponsors trust that we are looking towards matters that can have significant practical and financial implications. Not long ago that would have seemed far fetched. But electronics and communications revolutions have been revolutionizing seismology for decades. Many oil fields are already instrumented with multiple hundreds of geophones. We are now prepared to evaluate the prospects for the multiple tens of thousands of geophones that are already practical.