Ann: Cooper Basin Project Update , page-43

Opaline, Kiwigeo,
The geo-phones you observed may have been for listening to micro seismic events when they were doing the stimulation.
They had geophones in listening wells as well.
This technique was pioneered at Los Alamos decades ago when they were first looking at HDR geothermal, (enhanced geothermal as they call it).
It is possible to plot the events in time and space to made a 3D map of the enhancement as it progresses.

Granites exhibit natural fractures as a result of cooling, and are very uniform as all geologists know.
When a prominent fracture zone is encountered, observed by a number of things, faster drilling, maybe more torque, loss of mud, confirmed later by logging etc, it is a candidate for later enhancement. More than one of these fracture zones have been encountered in all of the wells they have drilled.

When enhanced the rock will yield depending on the minimum stress direction, in the Cooper Basin it is conveniently vertical, thus allowing the rock to move vertically, and thereby allowing the fracture to promulgate horizontally.
In Jolokia these zones were observed over a 1000m interval, so they are not just associated with cooling at the upper margin.

Basically
The fracture zones were expected, and observed when drilling.
They conveniently open vertically.
They are mapped during enhancement.