The seismic network used in this study is made up of seismometers operated by Mercury (all seismographs named RT and NS in Figure \ref{Figure2}), Contact Energy (THQ2, ARAZ), and GeoNet (WPRZ, PRRZ, HRRZ, ALRZ). From the beginning of 2012 to the end of 2015 the number of operational stations ranged from 15 to 29. The network covers an area roughly 30km (NE-SW) by 15km (NW-SE) with the bulk of the stations occupying an area 15km (N-S) by 7km (W-E) around the Rotokawa and Ngatamariki geothermal areas (Figure \ref{Figure1}). The Mercury surface stations are 4.5Hz Geospace GS-11D instruments whereas the Contact Energy station ARAZ is a 1.0Hz Mark Products L-4C3D sensor. Sites NS12, NS13 and NS14 are IESE borehole instruments installed at depths of between 200 and 514 meters.