Why would you need ground geophysics if you have a decline and are mining the deposits. It is far cheaper to drill and you have core. With Geophysics you have a wish and a prayer. You still have to drill to prove resource and follow veins. Basically it is a variation of seismic used to find oil with geophones and a vibroseis gas thumper. Just talked to a company about it at the Geological conference in Calgay last month.