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One can legitimately question the model details and parameter estimates but the point of this somewhat heuristic approach is not to be an accurate model. Rather, it is to give an indication of the flow rates that are needed to sustain the maximum observed thermal anomaly within the Dirtlow Rake and to assess whether these are reasonable. That the model may only be accurate to within a factor of 5 to 10 does not invalidate the central result that if fluid release occurs in a pulsed and episodic manner then each event must be of short duration to sustain the necessary thermal anomaly. Moreover the duration of these events and maximum flow rates associated with them are commensurate with fluid fluxes associated with modern observations of fluid behaviour following earthquake rupture.  These observations about the pulsed and rapid nature of fluid flow in MVT systems is are  convergent with ideas expressed by several researchers e.g. Cathles and Smith (1986), \citet{Bodnar:2009hc, Wilkinson06022009}. They also pose serious questions about our understanding concerning the transport and precipitation of carbonate minerals in fracture systems. For example modelling and experimental data on vein formation suggest that an extremely large volume of fluid is required to produce calcite veins in nature with fluid:calcite volume ratios of 10^{5} to 10^{6}. These same models also predict that the flow needs to be sustained for thousands to millions of years \citep{Lee_1996, Lee_1999}.