Ultra low noise +/-15V power supply
Use a linear power supply with a screened power transformer, good filtering, followed by linear low-noise regulators (eg. TI) followed by a bit of RC+ ferrite bead filtering. Or batteries + linear regulators etc.

If you really need to work from a 9VDC battery you would be better off redesigning the circuit to work from something like +/-2.5V than trying to insert a switching regulator and then cover up the noise. It's not impossible to do it as you suggest, it just requires a lot of care, to the point where most experienced consultants (ie. folks who have an idea of what's involved) are going to no-bid or greatly increase the cost to cover all the work. Geophones are some of the most demanding signal sources around, and if you want to get low nV/sqrt(Hz) noise spectral density down to fractions of a Hz a lot of care is required.  

Your signal bandwidth will probably be &lt; 10Hz but you do need to worry about higher frequencies, including RF, causing subtle low frequency noise through nonlinear behavior.